<?xml version="1.0" encoding="US-ASCII"?>
<!--XBRL Document Created with Wdesk from Workiva, formerly WebFilings-->
<!-- -->
<linkbase xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd" xmlns="http://www.xbrl.org/2003/linkbase" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <roleRef roleURI="http://www.emcorgroup.com/role/AcquisitionsOfBusinesses" xlink:href="eme-20140630.xsd#AcquisitionsOfBusinesses" xlink:type="simple" />
  <roleRef roleURI="http://www.emcorgroup.com/role/AcquisitionsOfBusinessesDetails" xlink:href="eme-20140630.xsd#AcquisitionsOfBusinessesDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.emcorgroup.com/role/BasisOfPresentation" xlink:href="eme-20140630.xsd#BasisOfPresentation" xlink:type="simple" />
  <roleRef roleURI="http://www.emcorgroup.com/role/CommitmentsAndContingencies" xlink:href="eme-20140630.xsd#CommitmentsAndContingencies" xlink:type="simple" />
  <roleRef roleURI="http://www.emcorgroup.com/role/CommitmentsAndContingenciesNarrativeDetails" xlink:href="eme-20140630.xsd#CommitmentsAndContingenciesNarrativeDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.emcorgroup.com/role/CommitmentsAndContingenciesRestructuringAndRelatedActivitiesTables" xlink:href="eme-20140630.xsd#CommitmentsAndContingenciesRestructuringAndRelatedActivitiesTables" xlink:type="simple" />
  <roleRef roleURI="http://www.emcorgroup.com/role/CommonStock" xlink:href="eme-20140630.xsd#CommonStock" xlink:type="simple" />
  <roleRef roleURI="http://www.emcorgroup.com/role/CommonStockDetails" xlink:href="eme-20140630.xsd#CommonStockDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.emcorgroup.com/role/CondensedConsolidatedBalanceSheets" xlink:href="eme-20140630.xsd#CondensedConsolidatedBalanceSheets" xlink:type="simple" />
  <roleRef roleURI="http://www.emcorgroup.com/role/CondensedConsolidatedBalanceSheetsParenthetical" xlink:href="eme-20140630.xsd#CondensedConsolidatedBalanceSheetsParenthetical" xlink:type="simple" />
  <roleRef roleURI="http://www.emcorgroup.com/role/CondensedConsolidatedStatementsOfCashFlows" xlink:href="eme-20140630.xsd#CondensedConsolidatedStatementsOfCashFlows" xlink:type="simple" />
  <roleRef roleURI="http://www.emcorgroup.com/role/CondensedConsolidatedStatementsOfComprehensiveIncome" xlink:href="eme-20140630.xsd#CondensedConsolidatedStatementsOfComprehensiveIncome" xlink:type="simple" />
  <roleRef roleURI="http://www.emcorgroup.com/role/CondensedConsolidatedStatementsOfComprehensiveIncomeParenthetical" xlink:href="eme-20140630.xsd#CondensedConsolidatedStatementsOfComprehensiveIncomeParenthetical" xlink:type="simple" />
  <roleRef roleURI="http://www.emcorgroup.com/role/CondensedConsolidatedStatementsOfEquity" xlink:href="eme-20140630.xsd#CondensedConsolidatedStatementsOfEquity" xlink:type="simple" />
  <roleRef roleURI="http://www.emcorgroup.com/role/CondensedConsolidatedStatementsOfEquityParenthetical" xlink:href="eme-20140630.xsd#CondensedConsolidatedStatementsOfEquityParenthetical" xlink:type="simple" />
  <roleRef roleURI="http://www.emcorgroup.com/role/CondensedConsolidatedStatementsOfOperations" xlink:href="eme-20140630.xsd#CondensedConsolidatedStatementsOfOperations" xlink:type="simple" />
  <roleRef roleURI="http://www.emcorgroup.com/role/Debt" xlink:href="eme-20140630.xsd#Debt" xlink:type="simple" />
  <roleRef roleURI="http://www.emcorgroup.com/role/DebtNarrativeDetails" xlink:href="eme-20140630.xsd#DebtNarrativeDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.emcorgroup.com/role/DebtScheduleOfDebtDetails" xlink:href="eme-20140630.xsd#DebtScheduleOfDebtDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.emcorgroup.com/role/DebtTables" xlink:href="eme-20140630.xsd#DebtTables" xlink:type="simple" />
  <roleRef roleURI="http://www.emcorgroup.com/role/DispositionOfAssets" xlink:href="eme-20140630.xsd#DispositionOfAssets" xlink:type="simple" />
  <roleRef roleURI="http://www.emcorgroup.com/role/DispositionOfAssetsNarrativeDetails" xlink:href="eme-20140630.xsd#DispositionOfAssetsNarrativeDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.emcorgroup.com/role/DocumentAndEntityInformation" xlink:href="eme-20140630.xsd#DocumentAndEntityInformation" xlink:type="simple" />
  <roleRef roleURI="http://www.emcorgroup.com/role/EarningsPerShare" xlink:href="eme-20140630.xsd#EarningsPerShare" xlink:type="simple" />
  <roleRef roleURI="http://www.emcorgroup.com/role/EarningsPerShareDetails" xlink:href="eme-20140630.xsd#EarningsPerShareDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.emcorgroup.com/role/EarningsPerShareTables" xlink:href="eme-20140630.xsd#EarningsPerShareTables" xlink:type="simple" />
  <roleRef roleURI="http://www.emcorgroup.com/role/FairValueMeasurements" xlink:href="eme-20140630.xsd#FairValueMeasurements" xlink:type="simple" />
  <roleRef roleURI="http://www.emcorgroup.com/role/FairValueMeasurementsPolicy" xlink:href="eme-20140630.xsd#FairValueMeasurementsPolicy" xlink:type="simple" />
  <roleRef roleURI="http://www.emcorgroup.com/role/FairValueMeasurementsScheduleOfAssetsAndLiabilitiesCarriedAtFairValueMeasuredOnRecurringBasisDetails" xlink:href="eme-20140630.xsd#FairValueMeasurementsScheduleOfAssetsAndLiabilitiesCarriedAtFairValueMeasuredOnRecurringBasisDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.emcorgroup.com/role/FairValueMeasurementsTables" xlink:href="eme-20140630.xsd#FairValueMeasurementsTables" xlink:type="simple" />
  <roleRef roleURI="http://www.emcorgroup.com/role/IncomeTaxes" xlink:href="eme-20140630.xsd#IncomeTaxes" xlink:type="simple" />
  <roleRef roleURI="http://www.emcorgroup.com/role/IncomeTaxesDetails" xlink:href="eme-20140630.xsd#IncomeTaxesDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.emcorgroup.com/role/Inventories" xlink:href="eme-20140630.xsd#Inventories" xlink:type="simple" />
  <roleRef roleURI="http://www.emcorgroup.com/role/InventoriesInventoriesDetails" xlink:href="eme-20140630.xsd#InventoriesInventoriesDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.emcorgroup.com/role/InventoriesTables" xlink:href="eme-20140630.xsd#InventoriesTables" xlink:type="simple" />
  <roleRef roleURI="http://www.emcorgroup.com/role/NewAccountingPronouncements" xlink:href="eme-20140630.xsd#NewAccountingPronouncements" xlink:type="simple" />
  <roleRef roleURI="http://www.emcorgroup.com/role/RetirementPlans" xlink:href="eme-20140630.xsd#RetirementPlans" xlink:type="simple" />
  <roleRef roleURI="http://www.emcorgroup.com/role/RetirementPlansComponentsOfNetPeriodicPensionBenefitCostDetails" xlink:href="eme-20140630.xsd#RetirementPlansComponentsOfNetPeriodicPensionBenefitCostDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.emcorgroup.com/role/RetirementPlansNarrativeDetails" xlink:href="eme-20140630.xsd#RetirementPlansNarrativeDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.emcorgroup.com/role/RetirementPlansTables" xlink:href="eme-20140630.xsd#RetirementPlansTables" xlink:type="simple" />
  <roleRef roleURI="http://www.emcorgroup.com/role/ScheduleOfRestructuringActivitiesDetails" xlink:href="eme-20140630.xsd#ScheduleOfRestructuringActivitiesDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.emcorgroup.com/role/SegmentInformation" xlink:href="eme-20140630.xsd#SegmentInformation" xlink:type="simple" />
  <roleRef roleURI="http://www.emcorgroup.com/role/SegmentInformationInformationAboutIndustrySegmentsAndGeographicAreasDetails" xlink:href="eme-20140630.xsd#SegmentInformationInformationAboutIndustrySegmentsAndGeographicAreasDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.emcorgroup.com/role/SegmentInformationTables" xlink:href="eme-20140630.xsd#SegmentInformationTables" xlink:type="simple" />
  <roleRef roleURI="http://www.emcorgroup.com/role/SubsequentEventsSubsequentEvents" xlink:href="eme-20140630.xsd#SubsequentEventsSubsequentEvents" xlink:type="simple" />
  <roleRef roleURI="http://www.emcorgroup.com/role/SubsequentEventsSubsequentEventsDetails" xlink:href="eme-20140630.xsd#SubsequentEventsSubsequentEventsDetails" xlink:type="simple" />
  <arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all" xlink:type="simple" />
  <arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default" xlink:type="simple" />
  <arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain" xlink:type="simple" />
  <arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member" xlink:type="simple" />
  <arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension" xlink:type="simple" />
  <definitionLink xlink:role="http://www.emcorgroup.com/role/AcquisitionsOfBusinesses" xlink:type="extended" />
  <definitionLink xlink:role="http://www.emcorgroup.com/role/AcquisitionsOfBusinessesDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_BusinessAcquisitionLineItems" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_8C940F01FEB5B1E5F4B0DEBBCDC4E4D6" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_6C5092647C6ACE5483E7DEBBCDC3BE05" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_8C940F01FEB5B1E5F4B0DEBBCDC4E4D6" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_6C5092647C6ACE5483E7DEBBCDC3BE05" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_81B7A7B425126A272DA2DEBBCDC324BC" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_6C5092647C6ACE5483E7DEBBCDC3BE05" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_81B7A7B425126A272DA2DEBBCDC324BC" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_ED7AE677F7D281CC420CDEBBCDC3F811_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_81B7A7B425126A272DA2DEBBCDC324BC" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_ED7AE677F7D281CC420CDEBBCDC3F811_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_ED7AE677F7D281CC420CDEBBCDC3F811" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_81B7A7B425126A272DA2DEBBCDC324BC" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_ED7AE677F7D281CC420CDEBBCDC3F811" xlink:type="arc" />
    <loc xlink:href="eme-20140630.xsd#eme_RepconStricklandMember" xlink:label="loc_eme_RepconStricklandMember_4041418DC54B343ABBBDDEBBCDC4B608" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_ED7AE677F7D281CC420CDEBBCDC3F811" xlink:to="loc_eme_RepconStricklandMember_4041418DC54B343ABBBDDEBBCDC4B608" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_BusinessAcquisitionEffectiveDateOfAcquisition1" xlink:label="loc_us-gaap_BusinessAcquisitionEffectiveDateOfAcquisition1_E3F5F4E4C7D63BC739DFDEBBCDC4E6B4" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_8C940F01FEB5B1E5F4B0DEBBCDC4E4D6" xlink:to="loc_us-gaap_BusinessAcquisitionEffectiveDateOfAcquisition1_E3F5F4E4C7D63BC739DFDEBBCDC4E6B4" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired" xlink:label="loc_us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired_30A6635221AFD9258A60DEBBCDC4D2A2" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_8C940F01FEB5B1E5F4B0DEBBCDC4E4D6" xlink:to="loc_us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired_30A6635221AFD9258A60DEBBCDC4D2A2" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_PaymentsToAcquireBusinessesGross" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesGross_79862FE6B78934CDC687DEBBCDC4ACF0" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_8C940F01FEB5B1E5F4B0DEBBCDC4E4D6" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesGross_79862FE6B78934CDC687DEBBCDC4ACF0" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ProceedsFromLinesOfCredit" xlink:label="loc_us-gaap_ProceedsFromLinesOfCredit_830BD4072A4E018DD265DEBBCDC40723" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_8C940F01FEB5B1E5F4B0DEBBCDC4E4D6" xlink:to="loc_us-gaap_ProceedsFromLinesOfCredit_830BD4072A4E018DD265DEBBCDC40723" xlink:type="arc" />
    <loc xlink:href="eme-20140630.xsd#eme_BusinessCombinationRecognizedWorkingCapital" xlink:label="loc_eme_BusinessCombinationRecognizedWorkingCapital_058C435BF86A20BE6749DEBBCDC44322" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_8C940F01FEB5B1E5F4B0DEBBCDC4E4D6" xlink:to="loc_eme_BusinessCombinationRecognizedWorkingCapital_058C435BF86A20BE6749DEBBCDC44322" xlink:type="arc" />
    <loc xlink:href="eme-20140630.xsd#eme_BusinessCombinationRecognizedOtherNetLiabilities" xlink:label="loc_eme_BusinessCombinationRecognizedOtherNetLiabilities_753CF777E76E712EEE37DEBBCDC429B3" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_8C940F01FEB5B1E5F4B0DEBBCDC4E4D6" xlink:to="loc_eme_BusinessCombinationRecognizedOtherNetLiabilities_753CF777E76E712EEE37DEBBCDC429B3" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_Goodwill" xlink:label="loc_us-gaap_Goodwill_9695DE1E6F2ABFA6ECFFDEBBCDC4F56D" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_8C940F01FEB5B1E5F4B0DEBBCDC4E4D6" xlink:to="loc_us-gaap_Goodwill_9695DE1E6F2ABFA6ECFFDEBBCDC4F56D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill_004D27D81EF174304753DEBBCDC4EC41" xlink:type="locator" />
    <definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_8C940F01FEB5B1E5F4B0DEBBCDC4E4D6" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill_004D27D81EF174304753DEBBCDC4EC41" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_BusinessAcquisitionPurchasePriceAllocationGoodwillExpectedTaxDeductibleAmount" xlink:label="loc_us-gaap_BusinessAcquisitionPurchasePriceAllocationGoodwillExpectedTaxDeductibleAmount_B70038525D28D5FB8BFCDEBBCDC4F4E5" xlink:type="locator" />
    <definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_8C940F01FEB5B1E5F4B0DEBBCDC4E4D6" xlink:to="loc_us-gaap_BusinessAcquisitionPurchasePriceAllocationGoodwillExpectedTaxDeductibleAmount_B70038525D28D5FB8BFCDEBBCDC4F4E5" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_NumberOfBusinessesAcquired" xlink:label="loc_us-gaap_NumberOfBusinessesAcquired_03E9AF327D811E0FE7A7DEBBCDC4230A" xlink:type="locator" />
    <definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_8C940F01FEB5B1E5F4B0DEBBCDC4E4D6" xlink:to="loc_us-gaap_NumberOfBusinessesAcquired_03E9AF327D811E0FE7A7DEBBCDC4230A" xlink:type="arc" />
    <loc xlink:href="eme-20140630.xsd#eme_NonCashIncomeExpenseFromContingentConsiderationArrangements" xlink:label="loc_eme_NonCashIncomeExpenseFromContingentConsiderationArrangements_9C425E38204166E61DF6DEBBCDC40FA6" xlink:type="locator" />
    <definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_8C940F01FEB5B1E5F4B0DEBBCDC4E4D6" xlink:to="loc_eme_NonCashIncomeExpenseFromContingentConsiderationArrangements_9C425E38204166E61DF6DEBBCDC40FA6" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.emcorgroup.com/role/BasisOfPresentation" xlink:type="extended" />
  <definitionLink xlink:role="http://www.emcorgroup.com/role/CommitmentsAndContingencies" xlink:type="extended" />
  <definitionLink xlink:role="http://www.emcorgroup.com/role/CommitmentsAndContingenciesNarrativeDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_LossContingenciesLineItems" xlink:label="loc_us-gaap_LossContingenciesLineItems_B95DA9F309E61FD478C6DEBBCE1D0B84" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_LossContingenciesTable" xlink:label="loc_us-gaap_LossContingenciesTable_A34E5B745AFDD32F7D7BDEBBCE1C03D1" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LossContingenciesLineItems_B95DA9F309E61FD478C6DEBBCE1D0B84" xlink:to="loc_us-gaap_LossContingenciesTable_A34E5B745AFDD32F7D7BDEBBCE1C03D1" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_RestructuringCostAndReserveAxis" xlink:label="loc_us-gaap_RestructuringCostAndReserveAxis_A6592D2EF15344F06AACDEBBCE1C0BE5" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_A34E5B745AFDD32F7D7BDEBBCE1C03D1" xlink:to="loc_us-gaap_RestructuringCostAndReserveAxis_A6592D2EF15344F06AACDEBBCE1C0BE5" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_TypeOfRestructuringDomain" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_D5BDFD450C9E92EC830CDEBBCE1C397F_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_A6592D2EF15344F06AACDEBBCE1C0BE5" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_D5BDFD450C9E92EC830CDEBBCE1C397F_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_TypeOfRestructuringDomain" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_D5BDFD450C9E92EC830CDEBBCE1C397F" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_A6592D2EF15344F06AACDEBBCE1C0BE5" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_D5BDFD450C9E92EC830CDEBBCE1C397F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_EmployeeSeveranceMember" xlink:label="loc_us-gaap_EmployeeSeveranceMember_DECB0C759B1C42DF0625DEBBCE1C358F" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_D5BDFD450C9E92EC830CDEBBCE1C397F" xlink:to="loc_us-gaap_EmployeeSeveranceMember_DECB0C759B1C42DF0625DEBBCE1C358F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FacilityClosingMember" xlink:label="loc_us-gaap_FacilityClosingMember_613DDE7BCE14D5EDE7EDDEBBCE1C4568" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_D5BDFD450C9E92EC830CDEBBCE1C397F" xlink:to="loc_us-gaap_FacilityClosingMember_613DDE7BCE14D5EDE7EDDEBBCE1C4568" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_LossContingenciesByNatureOfContingencyAxis" xlink:label="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_7208D4AF8BBF95BB5AC1DEBBCE1C9FBB" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_A34E5B745AFDD32F7D7BDEBBCE1C03D1" xlink:to="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_7208D4AF8BBF95BB5AC1DEBBCE1C9FBB" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_LossContingencyNatureDomain" xlink:label="loc_us-gaap_LossContingencyNatureDomain_65AC463483272AD5B561DEBBCE1C20C6_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_7208D4AF8BBF95BB5AC1DEBBCE1C9FBB" xlink:to="loc_us-gaap_LossContingencyNatureDomain_65AC463483272AD5B561DEBBCE1C20C6_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_LossContingencyNatureDomain" xlink:label="loc_us-gaap_LossContingencyNatureDomain_65AC463483272AD5B561DEBBCE1C20C6" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_7208D4AF8BBF95BB5AC1DEBBCE1C9FBB" xlink:to="loc_us-gaap_LossContingencyNatureDomain_65AC463483272AD5B561DEBBCE1C20C6" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_LitigationStatusAxis" xlink:label="loc_us-gaap_LitigationStatusAxis_5EF739E823582144E1CFDEBBCE1C9C4A" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_A34E5B745AFDD32F7D7BDEBBCE1C03D1" xlink:to="loc_us-gaap_LitigationStatusAxis_5EF739E823582144E1CFDEBBCE1C9C4A" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_LitigationStatusDomain" xlink:label="loc_us-gaap_LitigationStatusDomain_904F54C5900523008F74DEBBCE1C6812_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LitigationStatusAxis_5EF739E823582144E1CFDEBBCE1C9C4A" xlink:to="loc_us-gaap_LitigationStatusDomain_904F54C5900523008F74DEBBCE1C6812_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_LitigationStatusDomain" xlink:label="loc_us-gaap_LitigationStatusDomain_904F54C5900523008F74DEBBCE1C6812" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LitigationStatusAxis_5EF739E823582144E1CFDEBBCE1C9C4A" xlink:to="loc_us-gaap_LitigationStatusDomain_904F54C5900523008F74DEBBCE1C6812" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_LitigationCaseAxis" xlink:label="loc_us-gaap_LitigationCaseAxis_A46A7A597ABE30728C64DEBBCE1D9686" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_A34E5B745AFDD32F7D7BDEBBCE1C03D1" xlink:to="loc_us-gaap_LitigationCaseAxis_A46A7A597ABE30728C64DEBBCE1D9686" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_LitigationCaseTypeDomain" xlink:label="loc_us-gaap_LitigationCaseTypeDomain_D3812854FF343A4C51B3DEBBCE1D593C_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LitigationCaseAxis_A46A7A597ABE30728C64DEBBCE1D9686" xlink:to="loc_us-gaap_LitigationCaseTypeDomain_D3812854FF343A4C51B3DEBBCE1D593C_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_LitigationCaseTypeDomain" xlink:label="loc_us-gaap_LitigationCaseTypeDomain_D3812854FF343A4C51B3DEBBCE1D593C" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LitigationCaseAxis_A46A7A597ABE30728C64DEBBCE1D9686" xlink:to="loc_us-gaap_LitigationCaseTypeDomain_D3812854FF343A4C51B3DEBBCE1D593C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_RestructuringCharges" xlink:label="loc_us-gaap_RestructuringCharges_F5F805BFAFC1B2D6AA04DEBBCE1DF0D3" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_B95DA9F309E61FD478C6DEBBCE1D0B84" xlink:to="loc_us-gaap_RestructuringCharges_F5F805BFAFC1B2D6AA04DEBBCE1DF0D3" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_RestructuringReserve" xlink:label="loc_us-gaap_RestructuringReserve_5EB1327CB30869996326DEBBCE1D6655" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_B95DA9F309E61FD478C6DEBBCE1D0B84" xlink:to="loc_us-gaap_RestructuringReserve_5EB1327CB30869996326DEBBCE1D6655" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_RestructuringAndRelatedCostExpectedCostRemaining1" xlink:label="loc_us-gaap_RestructuringAndRelatedCostExpectedCostRemaining1_7A4183C931BD0F8E5F7DDEBBCE1D3CE8" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_B95DA9F309E61FD478C6DEBBCE1D0B84" xlink:to="loc_us-gaap_RestructuringAndRelatedCostExpectedCostRemaining1_7A4183C931BD0F8E5F7DDEBBCE1D3CE8" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.emcorgroup.com/role/CommitmentsAndContingenciesRestructuringAndRelatedActivitiesTables" xlink:type="extended" />
  <definitionLink xlink:role="http://www.emcorgroup.com/role/CommonStock" xlink:type="extended" />
  <definitionLink xlink:role="http://www.emcorgroup.com/role/CommonStockDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_EquityClassOfTreasuryStockLineItems" xlink:label="loc_us-gaap_EquityClassOfTreasuryStockLineItems_1C733A2CFBF9AE89CD0F182A488BDA38" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ClassOfTreasuryStockTable" xlink:label="loc_us-gaap_ClassOfTreasuryStockTable_8FA9198D0C52A430BD04182A488A18F9" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_1C733A2CFBF9AE89CD0F182A488BDA38" xlink:to="loc_us-gaap_ClassOfTreasuryStockTable_8FA9198D0C52A430BD04182A488A18F9" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis_F7CE378BFF23FBBABC88182A488A75F3" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ClassOfTreasuryStockTable_8FA9198D0C52A430BD04182A488A18F9" xlink:to="loc_us-gaap_StatementClassOfStockAxis_F7CE378BFF23FBBABC88182A488A75F3" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_B6ECCA8B4B87784CFF7E182A488B84BE_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_F7CE378BFF23FBBABC88182A488A75F3" xlink:to="loc_us-gaap_ClassOfStockDomain_B6ECCA8B4B87784CFF7E182A488B84BE_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_B6ECCA8B4B87784CFF7E182A488B84BE" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_F7CE378BFF23FBBABC88182A488A75F3" xlink:to="loc_us-gaap_ClassOfStockDomain_B6ECCA8B4B87784CFF7E182A488B84BE" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ShareRepurchaseProgramAxis" xlink:label="loc_us-gaap_ShareRepurchaseProgramAxis_3EC096EA2133882DCA11182A488BACB4" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ClassOfTreasuryStockTable_8FA9198D0C52A430BD04182A488A18F9" xlink:to="loc_us-gaap_ShareRepurchaseProgramAxis_3EC096EA2133882DCA11182A488BACB4" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ShareRepurchaseProgramDomain" xlink:label="loc_us-gaap_ShareRepurchaseProgramDomain_B56D63FB9120E34186D0182A488B7EF2_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ShareRepurchaseProgramAxis_3EC096EA2133882DCA11182A488BACB4" xlink:to="loc_us-gaap_ShareRepurchaseProgramDomain_B56D63FB9120E34186D0182A488B7EF2_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ShareRepurchaseProgramDomain" xlink:label="loc_us-gaap_ShareRepurchaseProgramDomain_B56D63FB9120E34186D0182A488B7EF2" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ShareRepurchaseProgramAxis_3EC096EA2133882DCA11182A488BACB4" xlink:to="loc_us-gaap_ShareRepurchaseProgramDomain_B56D63FB9120E34186D0182A488B7EF2" xlink:type="arc" />
    <loc xlink:href="eme-20140630.xsd#eme_RepurchaseProgramSep262011Member" xlink:label="loc_eme_RepurchaseProgramSep262011Member_E2D8F2417369197BA181182A488BE9CB" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareRepurchaseProgramDomain_B56D63FB9120E34186D0182A488B7EF2" xlink:to="loc_eme_RepurchaseProgramSep262011Member_E2D8F2417369197BA181182A488BE9CB" xlink:type="arc" />
    <loc xlink:href="eme-20140630.xsd#eme_RepurchaseProgramDec052013Member" xlink:label="loc_eme_RepurchaseProgramDec052013Member_EC3EF3AC7677E1E115C0182A488B2590" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareRepurchaseProgramDomain_B56D63FB9120E34186D0182A488B7EF2" xlink:to="loc_eme_RepurchaseProgramDec052013Member_EC3EF3AC7677E1E115C0182A488B2590" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_CommonStockSharesOutstanding" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_67BEC9E8CC951EA352AE182A488BD019" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_1C733A2CFBF9AE89CD0F182A488BDA38" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_67BEC9E8CC951EA352AE182A488BD019" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensationGross" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensationGross_768304F768252178A8AA182A488B8BDE" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_1C733A2CFBF9AE89CD0F182A488BDA38" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensationGross_768304F768252178A8AA182A488B8BDE" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StockRepurchaseProgramAuthorizedAmount1" xlink:label="loc_us-gaap_StockRepurchaseProgramAuthorizedAmount1_D6D47233277114E8CE9A182A488BBAC0" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_1C733A2CFBF9AE89CD0F182A488BDA38" xlink:to="loc_us-gaap_StockRepurchaseProgramAuthorizedAmount1_D6D47233277114E8CE9A182A488BBAC0" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StockRepurchasedDuringPeriodShares" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodShares_C9A142342F264047735A182A488B03BC" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_1C733A2CFBF9AE89CD0F182A488BDA38" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodShares_C9A142342F264047735A182A488B03BC" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StockRepurchasedDuringPeriodValue" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodValue_5CDA6D07A86B1E080FDA182A488BFE0A" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_1C733A2CFBF9AE89CD0F182A488BDA38" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodValue_5CDA6D07A86B1E080FDA182A488BFE0A" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1" xlink:label="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1_AEC10FF0210363684880182A488B07FD" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_1C733A2CFBF9AE89CD0F182A488BDA38" xlink:to="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1_AEC10FF0210363684880182A488B07FD" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.emcorgroup.com/role/CondensedConsolidatedBalanceSheets" xlink:type="extended" />
  <definitionLink xlink:role="http://www.emcorgroup.com/role/CondensedConsolidatedBalanceSheetsParenthetical" xlink:type="extended" />
  <definitionLink xlink:role="http://www.emcorgroup.com/role/CondensedConsolidatedStatementsOfCashFlows" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_72412FD601644D438ABB5031751E20D4" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_3EC29E9AD6F9C19D238E5031751E4642" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_72412FD601644D438ABB5031751E20D4" xlink:to="loc_us-gaap_StatementTable_3EC29E9AD6F9C19D238E5031751E4642" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StatementScenarioAxis" xlink:label="loc_us-gaap_StatementScenarioAxis_C992B7DC87031210B9B15031751ECBCA" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_3EC29E9AD6F9C19D238E5031751E4642" xlink:to="loc_us-gaap_StatementScenarioAxis_C992B7DC87031210B9B15031751ECBCA" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain" xlink:label="loc_us-gaap_ScenarioUnspecifiedDomain_FC05AF5D6097F4ACC0ED5031751E0890_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementScenarioAxis_C992B7DC87031210B9B15031751ECBCA" xlink:to="loc_us-gaap_ScenarioUnspecifiedDomain_FC05AF5D6097F4ACC0ED5031751E0890_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain" xlink:label="loc_us-gaap_ScenarioUnspecifiedDomain_FC05AF5D6097F4ACC0ED5031751E0890" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementScenarioAxis_C992B7DC87031210B9B15031751ECBCA" xlink:to="loc_us-gaap_ScenarioUnspecifiedDomain_FC05AF5D6097F4ACC0ED5031751E0890" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_A7C47BF57FD06FB2C6215031751EC721" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_72412FD601644D438ABB5031751E20D4" xlink:to="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_A7C47BF57FD06FB2C6215031751EC721" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ProfitLoss" xlink:label="loc_us-gaap_ProfitLoss_6F258C1336E03BBF2D235031751E284A" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_A7C47BF57FD06FB2C6215031751EC721" xlink:to="loc_us-gaap_ProfitLoss_6F258C1336E03BBF2D235031751E284A" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_Depreciation" xlink:label="loc_us-gaap_Depreciation_0E103346172CCAD269315031751F8185" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_A7C47BF57FD06FB2C6215031751EC721" xlink:to="loc_us-gaap_Depreciation_0E103346172CCAD269315031751F8185" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AmortizationOfIntangibleAssets" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_5EA32745938620B4D7065031751FEE6D" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_A7C47BF57FD06FB2C6215031751EC721" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_5EA32745938620B4D7065031751FEE6D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DeferredIncomeTaxExpenseBenefit" xlink:label="loc_us-gaap_DeferredIncomeTaxExpenseBenefit_E390F0E7FC02A3F6D52E5031751FF004" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_A7C47BF57FD06FB2C6215031751EC721" xlink:to="loc_us-gaap_DeferredIncomeTaxExpenseBenefit_E390F0E7FC02A3F6D52E5031751FF004" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_GainLossOnSaleOfBusiness" xlink:label="loc_us-gaap_GainLossOnSaleOfBusiness_A1FCAC1FD766434E1DD95031751F8E71" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_A7C47BF57FD06FB2C6215031751EC721" xlink:to="loc_us-gaap_GainLossOnSaleOfBusiness_A1FCAC1FD766434E1DD95031751F8E71" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ExcessTaxBenefitFromShareBasedCompensationOperatingActivities" xlink:label="loc_us-gaap_ExcessTaxBenefitFromShareBasedCompensationOperatingActivities_1448705B37E69E60F54B5031751F0941" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_A7C47BF57FD06FB2C6215031751EC721" xlink:to="loc_us-gaap_ExcessTaxBenefitFromShareBasedCompensationOperatingActivities_1448705B37E69E60F54B5031751F0941" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_IncomeLossFromEquityMethodInvestments" xlink:label="loc_us-gaap_IncomeLossFromEquityMethodInvestments_F87175E156D7B04D45975031751FE956" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_A7C47BF57FD06FB2C6215031751EC721" xlink:to="loc_us-gaap_IncomeLossFromEquityMethodInvestments_F87175E156D7B04D45975031751FE956" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_OtherNoncashIncomeExpense" xlink:label="loc_us-gaap_OtherNoncashIncomeExpense_D2494C016148AD47CE615031751F8C85" xlink:type="locator" />
    <definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_A7C47BF57FD06FB2C6215031751EC721" xlink:to="loc_us-gaap_OtherNoncashIncomeExpense_D2494C016148AD47CE615031751F8C85" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_EquityMethodInvestmentDividendsOrDistributions" xlink:label="loc_us-gaap_EquityMethodInvestmentDividendsOrDistributions_28EBEAC62C1F62C2ED8E5031751F47F7" xlink:type="locator" />
    <definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_A7C47BF57FD06FB2C6215031751EC721" xlink:to="loc_us-gaap_EquityMethodInvestmentDividendsOrDistributions_28EBEAC62C1F62C2ED8E5031751F47F7" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_IncreaseDecreaseInOperatingCapital" xlink:label="loc_us-gaap_IncreaseDecreaseInOperatingCapital_CBBA9859F6E5F5B859475031751F63FD" xlink:type="locator" />
    <definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_A7C47BF57FD06FB2C6215031751EC721" xlink:to="loc_us-gaap_IncreaseDecreaseInOperatingCapital_CBBA9859F6E5F5B859475031751F63FD" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_DBC0A1E594BE00A6B0B95031751F3301" xlink:type="locator" />
    <definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_A7C47BF57FD06FB2C6215031751EC721" xlink:to="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_DBC0A1E594BE00A6B0B95031751F3301" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_BEAFA25CB2B19E2038545031751F4FF1" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_72412FD601644D438ABB5031751E20D4" xlink:to="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_BEAFA25CB2B19E2038545031751F4FF1" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_652FB4A6A41AFC1A6EFE5031751FD26A" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_BEAFA25CB2B19E2038545031751F4FF1" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_652FB4A6A41AFC1A6EFE5031751FD26A" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ProceedsFromDivestitureOfBusinesses" xlink:label="loc_us-gaap_ProceedsFromDivestitureOfBusinesses_CC89D5E097D001AF2A595031751F7685" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_BEAFA25CB2B19E2038545031751F4FF1" xlink:to="loc_us-gaap_ProceedsFromDivestitureOfBusinesses_CC89D5E097D001AF2A595031751F7685" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ProceedsFromSaleOfPropertyPlantAndEquipment" xlink:label="loc_us-gaap_ProceedsFromSaleOfPropertyPlantAndEquipment_1F90802CD0265B8654295031751F5B3B" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_BEAFA25CB2B19E2038545031751F4FF1" xlink:to="loc_us-gaap_ProceedsFromSaleOfPropertyPlantAndEquipment_1F90802CD0265B8654295031751F5B3B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_PaymentsToAcquireProductiveAssets" xlink:label="loc_us-gaap_PaymentsToAcquireProductiveAssets_279ADAED9AAB34E4FB4E5031751F2B61" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_BEAFA25CB2B19E2038545031751F4FF1" xlink:to="loc_us-gaap_PaymentsToAcquireProductiveAssets_279ADAED9AAB34E4FB4E5031751F2B61" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_PaymentsToAcquireShortTermInvestments" xlink:label="loc_us-gaap_PaymentsToAcquireShortTermInvestments_36AD53E151D69AC0543A503175200821" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_BEAFA25CB2B19E2038545031751F4FF1" xlink:to="loc_us-gaap_PaymentsToAcquireShortTermInvestments_36AD53E151D69AC0543A503175200821" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ProceedsFromSaleMaturityAndCollectionOfShorttermInvestments" xlink:label="loc_us-gaap_ProceedsFromSaleMaturityAndCollectionOfShorttermInvestments_5F1B823C7A278D420BC550317520B522" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_BEAFA25CB2B19E2038545031751F4FF1" xlink:to="loc_us-gaap_ProceedsFromSaleMaturityAndCollectionOfShorttermInvestments_5F1B823C7A278D420BC550317520B522" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_PaymentsToAcquireEquityMethodInvestments" xlink:label="loc_us-gaap_PaymentsToAcquireEquityMethodInvestments_7D7DA606A0EB59673BE2503175202712" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_BEAFA25CB2B19E2038545031751F4FF1" xlink:to="loc_us-gaap_PaymentsToAcquireEquityMethodInvestments_7D7DA606A0EB59673BE2503175202712" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_DA331C318F2B011E6A1350317520C530" xlink:type="locator" />
    <definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_BEAFA25CB2B19E2038545031751F4FF1" xlink:to="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_DA331C318F2B011E6A1350317520C530" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_940034A6E4C336A42F0B50317520C846" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_72412FD601644D438ABB5031751E20D4" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_940034A6E4C336A42F0B50317520C846" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ProceedsFromLinesOfCredit" xlink:label="loc_us-gaap_ProceedsFromLinesOfCredit_60B469955A53F0B800B550317520C21E" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_940034A6E4C336A42F0B50317520C846" xlink:to="loc_us-gaap_ProceedsFromLinesOfCredit_60B469955A53F0B800B550317520C21E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_RepaymentsOfLongTermDebt" xlink:label="loc_us-gaap_RepaymentsOfLongTermDebt_E478C44BF1C3F7D668B9503175251648" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_940034A6E4C336A42F0B50317520C846" xlink:to="loc_us-gaap_RepaymentsOfLongTermDebt_E478C44BF1C3F7D668B9503175251648" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_RepaymentsOfLongTermCapitalLeaseObligations" xlink:label="loc_us-gaap_RepaymentsOfLongTermCapitalLeaseObligations_389D9571AA62BF9ED7C8503175256575" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_940034A6E4C336A42F0B50317520C846" xlink:to="loc_us-gaap_RepaymentsOfLongTermCapitalLeaseObligations_389D9571AA62BF9ED7C8503175256575" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_PaymentsOfDividendsCommonStock" xlink:label="loc_us-gaap_PaymentsOfDividendsCommonStock_50709CD17989DC2A89C750317525EEBA" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_940034A6E4C336A42F0B50317520C846" xlink:to="loc_us-gaap_PaymentsOfDividendsCommonStock_50709CD17989DC2A89C750317525EEBA" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_PaymentsForRepurchaseOfCommonStock" xlink:label="loc_us-gaap_PaymentsForRepurchaseOfCommonStock_C38A8F2EE651B2136D9450317525BB8D" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_940034A6E4C336A42F0B50317520C846" xlink:to="loc_us-gaap_PaymentsForRepurchaseOfCommonStock_C38A8F2EE651B2136D9450317525BB8D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ProceedsFromStockOptionsExercised" xlink:label="loc_us-gaap_ProceedsFromStockOptionsExercised_FEBF014E93284623A1ED503175256FE8" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_940034A6E4C336A42F0B50317520C846" xlink:to="loc_us-gaap_ProceedsFromStockOptionsExercised_FEBF014E93284623A1ED503175256FE8" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation" xlink:label="loc_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_560BC2BE534A15492F44503175253DDF" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_940034A6E4C336A42F0B50317520C846" xlink:to="loc_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_560BC2BE534A15492F44503175253DDF" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ProceedsFromStockPlans" xlink:label="loc_us-gaap_ProceedsFromStockPlans_C1A62148F94E2AF8BBE2503175252302" xlink:type="locator" />
    <definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_940034A6E4C336A42F0B50317520C846" xlink:to="loc_us-gaap_ProceedsFromStockPlans_C1A62148F94E2AF8BBE2503175252302" xlink:type="arc" />
    <loc xlink:href="eme-20140630.xsd#eme_PaymentsForContingentConsiderationArrangements" xlink:label="loc_eme_PaymentsForContingentConsiderationArrangements_D2EDBE88F11C03C24F8E503175259C8E" xlink:type="locator" />
    <definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_940034A6E4C336A42F0B50317520C846" xlink:to="loc_eme_PaymentsForContingentConsiderationArrangements_D2EDBE88F11C03C24F8E503175259C8E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_PaymentsOfDividendsMinorityInterest" xlink:label="loc_us-gaap_PaymentsOfDividendsMinorityInterest_196AFF7E96EA2310BFFE50317525914D" xlink:type="locator" />
    <definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_940034A6E4C336A42F0B50317520C846" xlink:to="loc_us-gaap_PaymentsOfDividendsMinorityInterest_196AFF7E96EA2310BFFE50317525914D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ExcessTaxBenefitFromShareBasedCompensationFinancingActivities" xlink:label="loc_us-gaap_ExcessTaxBenefitFromShareBasedCompensationFinancingActivities_77269DC1CE6491920D9250317525B7E9" xlink:type="locator" />
    <definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_940034A6E4C336A42F0B50317520C846" xlink:to="loc_us-gaap_ExcessTaxBenefitFromShareBasedCompensationFinancingActivities_77269DC1CE6491920D9250317525B7E9" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_137CB7AF9F956D5F98D750317525E21A" xlink:type="locator" />
    <definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_940034A6E4C336A42F0B50317520C846" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_137CB7AF9F956D5F98D750317525E21A" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_EffectOfExchangeRateOnCashAndCashEquivalents" xlink:label="loc_us-gaap_EffectOfExchangeRateOnCashAndCashEquivalents_119FE7F75756D2299F9F503175269653" xlink:type="locator" />
    <definitionArc order="13" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_940034A6E4C336A42F0B50317520C846" xlink:to="loc_us-gaap_EffectOfExchangeRateOnCashAndCashEquivalents_119FE7F75756D2299F9F503175269653" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease" xlink:label="loc_us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease_7EE3410637E468387DFC50317526EA20" xlink:type="locator" />
    <definitionArc order="14" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_940034A6E4C336A42F0B50317520C846" xlink:to="loc_us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease_7EE3410637E468387DFC50317526EA20" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_297BF0DD72A816C9E613503175261EED" xlink:type="locator" />
    <definitionArc order="15" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_940034A6E4C336A42F0B50317520C846" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_297BF0DD72A816C9E613503175261EED" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_SupplementalCashFlowInformationAbstract" xlink:label="loc_us-gaap_SupplementalCashFlowInformationAbstract_C8D7FC6BB57EA2D0E3265031752676F1" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_72412FD601644D438ABB5031751E20D4" xlink:to="loc_us-gaap_SupplementalCashFlowInformationAbstract_C8D7FC6BB57EA2D0E3265031752676F1" xlink:type="arc" />
    <loc xlink:href="eme-20140630.xsd#eme_CashPaidForAbstract" xlink:label="loc_eme_CashPaidForAbstract_3F38EA55BC12A1CE01F4503175264425" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SupplementalCashFlowInformationAbstract_C8D7FC6BB57EA2D0E3265031752676F1" xlink:to="loc_eme_CashPaidForAbstract_3F38EA55BC12A1CE01F4503175264425" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_InterestPaid" xlink:label="loc_us-gaap_InterestPaid_DB7677FAA4B504C63EDC5031752631AA" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_eme_CashPaidForAbstract_3F38EA55BC12A1CE01F4503175264425" xlink:to="loc_us-gaap_InterestPaid_DB7677FAA4B504C63EDC5031752631AA" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_IncomeTaxesPaid" xlink:label="loc_us-gaap_IncomeTaxesPaid_EBFC00CA3767681CB00A50317526181A" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_eme_CashPaidForAbstract_3F38EA55BC12A1CE01F4503175264425" xlink:to="loc_us-gaap_IncomeTaxesPaid_EBFC00CA3767681CB00A50317526181A" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract" xlink:label="loc_us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract_6AE42E752D63C539EFC9503175264B7C" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SupplementalCashFlowInformationAbstract_C8D7FC6BB57EA2D0E3265031752676F1" xlink:to="loc_us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract_6AE42E752D63C539EFC9503175264B7C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_CapitalLeaseObligationsIncurred" xlink:label="loc_us-gaap_CapitalLeaseObligationsIncurred_A07A715695FD95D57A17503175262322" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract_6AE42E752D63C539EFC9503175264B7C" xlink:to="loc_us-gaap_CapitalLeaseObligationsIncurred_A07A715695FD95D57A17503175262322" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.emcorgroup.com/role/CondensedConsolidatedStatementsOfComprehensiveIncome" xlink:type="extended" />
  <definitionLink xlink:role="http://www.emcorgroup.com/role/CondensedConsolidatedStatementsOfComprehensiveIncomeParenthetical" xlink:type="extended" />
  <definitionLink xlink:role="http://www.emcorgroup.com/role/CondensedConsolidatedStatementsOfEquity" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_7F1972B5EEBD2FDB21D04EB2EC0D7134" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_FDDFA509EBC9010E3D3F4EB2EC0D955C" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_7F1972B5EEBD2FDB21D04EB2EC0D7134" xlink:to="loc_us-gaap_StatementTable_FDDFA509EBC9010E3D3F4EB2EC0D955C" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_50CDEFE61C9A048275B14EB2EC0DBFF5" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_FDDFA509EBC9010E3D3F4EB2EC0D955C" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_50CDEFE61C9A048275B14EB2EC0DBFF5" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_6FB5DA94E819087CC2E84EB2EC0D899D_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_50CDEFE61C9A048275B14EB2EC0DBFF5" xlink:to="loc_us-gaap_EquityComponentDomain_6FB5DA94E819087CC2E84EB2EC0D899D_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_6FB5DA94E819087CC2E84EB2EC0D899D" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_50CDEFE61C9A048275B14EB2EC0DBFF5" xlink:to="loc_us-gaap_EquityComponentDomain_6FB5DA94E819087CC2E84EB2EC0D899D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_CommonStockMember" xlink:label="loc_us-gaap_CommonStockMember_F8093303BF39029168354EB2EC0D3EA8" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_6FB5DA94E819087CC2E84EB2EC0D899D" xlink:to="loc_us-gaap_CommonStockMember_F8093303BF39029168354EB2EC0D3EA8" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AdditionalPaidInCapitalMember" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_25762CF3B264F08C85704EB2EC0D3E8F" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_6FB5DA94E819087CC2E84EB2EC0D899D" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_25762CF3B264F08C85704EB2EC0D3E8F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_FCEAC864FE5D966FE5134EB2EC0DAFAC" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_6FB5DA94E819087CC2E84EB2EC0D899D" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_FCEAC864FE5D966FE5134EB2EC0DAFAC" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_RetainedEarningsMember" xlink:label="loc_us-gaap_RetainedEarningsMember_5251B4F2BE741931121A4EB2EC0D9E7E" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_6FB5DA94E819087CC2E84EB2EC0D899D" xlink:to="loc_us-gaap_RetainedEarningsMember_5251B4F2BE741931121A4EB2EC0D9E7E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_TreasuryStockMember" xlink:label="loc_us-gaap_TreasuryStockMember_3779244EAB6D4FD440EE4EB2EC0DBF42" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_6FB5DA94E819087CC2E84EB2EC0D899D" xlink:to="loc_us-gaap_TreasuryStockMember_3779244EAB6D4FD440EE4EB2EC0DBF42" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_NoncontrollingInterestMember" xlink:label="loc_us-gaap_NoncontrollingInterestMember_D37355C4C9852A324FDB4EB2EC0D9CA4" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_6FB5DA94E819087CC2E84EB2EC0D899D" xlink:to="loc_us-gaap_NoncontrollingInterestMember_D37355C4C9852A324FDB4EB2EC0D9CA4" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_893FD7F27254700B9D764EB2EC0D0EA9" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_7F1972B5EEBD2FDB21D04EB2EC0D7134" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_893FD7F27254700B9D764EB2EC0D0EA9" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ProfitLoss" xlink:label="loc_us-gaap_ProfitLoss_83C468CBF527DE40C86B4EB2EC0D9271" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_7F1972B5EEBD2FDB21D04EB2EC0D7134" xlink:to="loc_us-gaap_ProfitLoss_83C468CBF527DE40C86B4EB2EC0D9271" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_DCC7776D15A5E63335714EB2EC0D2B27" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_7F1972B5EEBD2FDB21D04EB2EC0D7134" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_DCC7776D15A5E63335714EB2EC0D2B27" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation_FD4DDCA9CE7902716CF44EB2EC0DEF2B" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_7F1972B5EEBD2FDB21D04EB2EC0D7134" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation_FD4DDCA9CE7902716CF44EB2EC0DEF2B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan_8F889CBA18FB8405BDFF4EB2EC0D293F" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_7F1972B5EEBD2FDB21D04EB2EC0D7134" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan_8F889CBA18FB8405BDFF4EB2EC0D293F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DividendsCommonStock" xlink:label="loc_us-gaap_DividendsCommonStock_C950464E13745C5612F84EB2EC0E43E0" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_7F1972B5EEBD2FDB21D04EB2EC0D7134" xlink:to="loc_us-gaap_DividendsCommonStock_C950464E13745C5612F84EB2EC0E43E0" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StockRepurchasedDuringPeriodValue" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodValue_03662089F6067278D3DA4EB2EC0E7298" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_7F1972B5EEBD2FDB21D04EB2EC0D7134" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodValue_03662089F6067278D3DA4EB2EC0E7298" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders" xlink:label="loc_us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders_5ED38A066BEC2C7F95AF4EB2EC0E756D" xlink:type="locator" />
    <definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_7F1972B5EEBD2FDB21D04EB2EC0D7134" xlink:to="loc_us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders_5ED38A066BEC2C7F95AF4EB2EC0E756D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_00BA1107E07B5E1613D04EB2EC0E6D55" xlink:type="locator" />
    <definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_7F1972B5EEBD2FDB21D04EB2EC0D7134" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_00BA1107E07B5E1613D04EB2EC0E6D55" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.emcorgroup.com/role/CondensedConsolidatedStatementsOfEquityParenthetical" xlink:type="extended" />
  <definitionLink xlink:role="http://www.emcorgroup.com/role/CondensedConsolidatedStatementsOfOperations" xlink:type="extended" />
  <definitionLink xlink:role="http://www.emcorgroup.com/role/Debt" xlink:type="extended" />
  <definitionLink xlink:role="http://www.emcorgroup.com/role/DebtNarrativeDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_LineOfCreditFacilityLineItems" xlink:label="loc_us-gaap_LineOfCreditFacilityLineItems_CC4387FC899416EBF856DEBBCDB14137" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_LineOfCreditFacilityTable" xlink:label="loc_us-gaap_LineOfCreditFacilityTable_595721C10AC32F68C252DEBBCDB068F8" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_CC4387FC899416EBF856DEBBCDB14137" xlink:to="loc_us-gaap_LineOfCreditFacilityTable_595721C10AC32F68C252DEBBCDB068F8" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_VariableRateAxis" xlink:label="loc_us-gaap_VariableRateAxis_2B47F67DCFB19723CCEDDEBBCDB00829" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_595721C10AC32F68C252DEBBCDB068F8" xlink:to="loc_us-gaap_VariableRateAxis_2B47F67DCFB19723CCEDDEBBCDB00829" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_VariableRateDomain" xlink:label="loc_us-gaap_VariableRateDomain_D159F686A3147F9C1742DEBBCDB11C0D_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VariableRateAxis_2B47F67DCFB19723CCEDDEBBCDB00829" xlink:to="loc_us-gaap_VariableRateDomain_D159F686A3147F9C1742DEBBCDB11C0D_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_VariableRateDomain" xlink:label="loc_us-gaap_VariableRateDomain_D159F686A3147F9C1742DEBBCDB11C0D" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VariableRateAxis_2B47F67DCFB19723CCEDDEBBCDB00829" xlink:to="loc_us-gaap_VariableRateDomain_D159F686A3147F9C1742DEBBCDB11C0D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_PrimeRateMember" xlink:label="loc_us-gaap_PrimeRateMember_0B4B3C7F102AD4A38CFDDEBBCDB161E9" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_D159F686A3147F9C1742DEBBCDB11C0D" xlink:to="loc_us-gaap_PrimeRateMember_0B4B3C7F102AD4A38CFDDEBBCDB161E9" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_LondonInterbankOfferedRateLIBORMember" xlink:label="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_05942A50B1CB816B3477DEBBCDB16278" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_D159F686A3147F9C1742DEBBCDB11C0D" xlink:to="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_05942A50B1CB816B3477DEBBCDB16278" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis_18508451634436B09A0CDEBBCDB1CFE8" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_595721C10AC32F68C252DEBBCDB068F8" xlink:to="loc_us-gaap_RangeAxis_18508451634436B09A0CDEBBCDB1CFE8" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_2B6967DC0851CFFE0F2CDEBBCDB18458_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RangeAxis_18508451634436B09A0CDEBBCDB1CFE8" xlink:to="loc_us-gaap_RangeMember_2B6967DC0851CFFE0F2CDEBBCDB18458_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_2B6967DC0851CFFE0F2CDEBBCDB18458" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RangeAxis_18508451634436B09A0CDEBBCDB1CFE8" xlink:to="loc_us-gaap_RangeMember_2B6967DC0851CFFE0F2CDEBBCDB18458" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_MinimumMember" xlink:label="loc_us-gaap_MinimumMember_F1E1368C39F258C70943DEBBCDB145F5" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_2B6967DC0851CFFE0F2CDEBBCDB18458" xlink:to="loc_us-gaap_MinimumMember_F1E1368C39F258C70943DEBBCDB145F5" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_MaximumMember" xlink:label="loc_us-gaap_MaximumMember_46C9DE9A43E3AC19F39CDEBBCDB19313" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_2B6967DC0851CFFE0F2CDEBBCDB18458" xlink:to="loc_us-gaap_MaximumMember_46C9DE9A43E3AC19F39CDEBBCDB19313" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DebtInstrumentAxis" xlink:label="loc_us-gaap_DebtInstrumentAxis_6F552A3883C3B4031DF5DEBBCDB18214" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_595721C10AC32F68C252DEBBCDB068F8" xlink:to="loc_us-gaap_DebtInstrumentAxis_6F552A3883C3B4031DF5DEBBCDB18214" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_A71AE7F9BD731B370744DEBBCDB1FE57_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_6F552A3883C3B4031DF5DEBBCDB18214" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_A71AE7F9BD731B370744DEBBCDB1FE57_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_A71AE7F9BD731B370744DEBBCDB1FE57" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_6F552A3883C3B4031DF5DEBBCDB18214" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_A71AE7F9BD731B370744DEBBCDB1FE57" xlink:type="arc" />
    <loc xlink:href="eme-20140630.xsd#eme_CreditAgreement2011Member" xlink:label="loc_eme_CreditAgreement2011Member_DE8A1E0B363D762AC2E3DEBBCDB1F640" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_A71AE7F9BD731B370744DEBBCDB1FE57" xlink:to="loc_eme_CreditAgreement2011Member_DE8A1E0B363D762AC2E3DEBBCDB1F640" xlink:type="arc" />
    <loc xlink:href="eme-20140630.xsd#eme_CreditAgreement2013MemberMember" xlink:label="loc_eme_CreditAgreement2013MemberMember_3CB81AC257A619539D4EDEBBCDB17102" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_A71AE7F9BD731B370744DEBBCDB1FE57" xlink:to="loc_eme_CreditAgreement2013MemberMember_3CB81AC257A619539D4EDEBBCDB17102" xlink:type="arc" />
    <loc xlink:href="eme-20140630.xsd#eme_RevolvingCreditFacility2013MemberMember" xlink:label="loc_eme_RevolvingCreditFacility2013MemberMember_E4AC9614415653490BFEDEBBCDB147D5" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_A71AE7F9BD731B370744DEBBCDB1FE57" xlink:to="loc_eme_RevolvingCreditFacility2013MemberMember_E4AC9614415653490BFEDEBBCDB147D5" xlink:type="arc" />
    <loc xlink:href="eme-20140630.xsd#eme_TermLoan2013Member" xlink:label="loc_eme_TermLoan2013Member_D81F75A682A6DC9E4C0CDEBBCDB1B7A4" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_A71AE7F9BD731B370744DEBBCDB1FE57" xlink:to="loc_eme_TermLoan2013Member_D81F75A682A6DC9E4C0CDEBBCDB1B7A4" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_17D8B2027251B3037872DEBBCDB1EB61" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_CC4387FC899416EBF856DEBBCDB14137" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_17D8B2027251B3037872DEBBCDB1EB61" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_LongTermDebt" xlink:label="loc_us-gaap_LongTermDebt_A2C86658B79BE8B12F1ADEBBCDB2AFF5" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_CC4387FC899416EBF856DEBBCDB14137" xlink:to="loc_us-gaap_LongTermDebt_A2C86658B79BE8B12F1ADEBBCDB2AFF5" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_LineOfCreditFacilityExpirationDate1" xlink:label="loc_us-gaap_LineOfCreditFacilityExpirationDate1_5079D3DA1F2E2BB836FEDEBBCDB23ECC" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_CC4387FC899416EBF856DEBBCDB14137" xlink:to="loc_us-gaap_LineOfCreditFacilityExpirationDate1_5079D3DA1F2E2BB836FEDEBBCDB23ECC" xlink:type="arc" />
    <loc xlink:href="eme-20140630.xsd#eme_IncreaseBorrowingCapacity" xlink:label="loc_eme_IncreaseBorrowingCapacity_4D57CFF58E6F9EB98981DEBBCDB2ACFE" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_CC4387FC899416EBF856DEBBCDB14137" xlink:to="loc_eme_IncreaseBorrowingCapacity_4D57CFF58E6F9EB98981DEBBCDB2ACFE" xlink:type="arc" />
    <loc xlink:href="eme-20140630.xsd#eme_LettersOfCreditMaximumBorrowingCapacity" xlink:label="loc_eme_LettersOfCreditMaximumBorrowingCapacity_85D0A06AF946F7EC0C44DEBBCDB22E5F" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_CC4387FC899416EBF856DEBBCDB14137" xlink:to="loc_eme_LettersOfCreditMaximumBorrowingCapacity_85D0A06AF946F7EC0C44DEBBCDB22E5F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage" xlink:label="loc_us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage_37BCDBDC11FC377F4DC2DEBBCDB26744" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_CC4387FC899416EBF856DEBBCDB14137" xlink:to="loc_us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage_37BCDBDC11FC377F4DC2DEBBCDB26744" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_LineOfCreditFacilityInterestRateDescription" xlink:label="loc_us-gaap_LineOfCreditFacilityInterestRateDescription_FB4B410BF90F74C30354DEBBCDB26D7B" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_CC4387FC899416EBF856DEBBCDB14137" xlink:to="loc_us-gaap_LineOfCreditFacilityInterestRateDescription_FB4B410BF90F74C30354DEBBCDB26D7B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_LongTermDebtPercentageBearingVariableInterestRate" xlink:label="loc_us-gaap_LongTermDebtPercentageBearingVariableInterestRate_07EBAC8BB248E785E7FCDEBBCDB2A225" xlink:type="locator" />
    <definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_CC4387FC899416EBF856DEBBCDB14137" xlink:to="loc_us-gaap_LongTermDebtPercentageBearingVariableInterestRate_07EBAC8BB248E785E7FCDEBBCDB2A225" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_A7C78693C7E23D967AADDEBBCDB26364" xlink:type="locator" />
    <definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_CC4387FC899416EBF856DEBBCDB14137" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_A7C78693C7E23D967AADDEBBCDB26364" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_LineOfCreditFacilityInterestRateAtPeriodEnd" xlink:label="loc_us-gaap_LineOfCreditFacilityInterestRateAtPeriodEnd_6833AD3485BE56DD77E1DEBBCDB2A0EF" xlink:type="locator" />
    <definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_CC4387FC899416EBF856DEBBCDB14137" xlink:to="loc_us-gaap_LineOfCreditFacilityInterestRateAtPeriodEnd_6833AD3485BE56DD77E1DEBBCDB2A0EF" xlink:type="arc" />
    <loc xlink:href="eme-20140630.xsd#eme_RangeOfLetterOfCreditFees" xlink:label="loc_eme_RangeOfLetterOfCreditFees_EB0AD706F34891FB628DDEBBCDB2C06E" xlink:type="locator" />
    <definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_CC4387FC899416EBF856DEBBCDB14137" xlink:to="loc_eme_RangeOfLetterOfCreditFees_EB0AD706F34891FB628DDEBBCDB2C06E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DeferredFinanceCostsGross" xlink:label="loc_us-gaap_DeferredFinanceCostsGross_6FBFE94C559D3CDDEF3FDEBBCDB280A3" xlink:type="locator" />
    <definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_CC4387FC899416EBF856DEBBCDB14137" xlink:to="loc_us-gaap_DeferredFinanceCostsGross_6FBFE94C559D3CDDEF3FDEBBCDB280A3" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DebtInstrumentPeriodicPaymentPrincipal" xlink:label="loc_us-gaap_DebtInstrumentPeriodicPaymentPrincipal_7E2787CA898BCA3C5D33DEBBCDB2082F" xlink:type="locator" />
    <definitionArc order="13" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_CC4387FC899416EBF856DEBBCDB14137" xlink:to="loc_us-gaap_DebtInstrumentPeriodicPaymentPrincipal_7E2787CA898BCA3C5D33DEBBCDB2082F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_LettersOfCreditOutstandingAmount" xlink:label="loc_us-gaap_LettersOfCreditOutstandingAmount_18316E918A0BF417B2F5DEBBCDB2B204" xlink:type="locator" />
    <definitionArc order="14" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_CC4387FC899416EBF856DEBBCDB14137" xlink:to="loc_us-gaap_LettersOfCreditOutstandingAmount_18316E918A0BF417B2F5DEBBCDB2B204" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_LongTermLineOfCredit" xlink:label="loc_us-gaap_LongTermLineOfCredit_0E930DDDDB8A1D19525EDEBBCDB2A21E" xlink:type="locator" />
    <definitionArc order="15" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_CC4387FC899416EBF856DEBBCDB14137" xlink:to="loc_us-gaap_LongTermLineOfCredit_0E930DDDDB8A1D19525EDEBBCDB2A21E" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.emcorgroup.com/role/DebtScheduleOfDebtDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="loc_us-gaap_DebtInstrumentLineItems_2BD04E34EF51AB119A607DEA0BB5CCE5" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DebtInstrumentTable" xlink:label="loc_us-gaap_DebtInstrumentTable_0D5C3BF72281F7EF7ECE7DEA0BB4B07F" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2BD04E34EF51AB119A607DEA0BB5CCE5" xlink:to="loc_us-gaap_DebtInstrumentTable_0D5C3BF72281F7EF7ECE7DEA0BB4B07F" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DebtInstrumentAxis" xlink:label="loc_us-gaap_DebtInstrumentAxis_A65B63A3B3FBCFAAF58A7DEA0BB46220" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_0D5C3BF72281F7EF7ECE7DEA0BB4B07F" xlink:to="loc_us-gaap_DebtInstrumentAxis_A65B63A3B3FBCFAAF58A7DEA0BB46220" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_7588C5C7131F9A0DB0C07DEA0BB4D325_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_A65B63A3B3FBCFAAF58A7DEA0BB46220" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_7588C5C7131F9A0DB0C07DEA0BB4D325_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_7588C5C7131F9A0DB0C07DEA0BB4D325" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_A65B63A3B3FBCFAAF58A7DEA0BB46220" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_7588C5C7131F9A0DB0C07DEA0BB4D325" xlink:type="arc" />
    <loc xlink:href="eme-20140630.xsd#eme_TermLoan2013Member" xlink:label="loc_eme_TermLoan2013Member_65D64B4FF503AC3CF04B7DEA0BB46A1A" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_7588C5C7131F9A0DB0C07DEA0BB4D325" xlink:to="loc_eme_TermLoan2013Member_65D64B4FF503AC3CF04B7DEA0BB46A1A" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_LongtermDebtTypeAxis" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_B1C4A33172E9544F6F157DEA0BB46E2E" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_0D5C3BF72281F7EF7ECE7DEA0BB4B07F" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_B1C4A33172E9544F6F157DEA0BB46E2E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_B5F3FCA31BAB2408E2E07DEA0BB5E5AC_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_B1C4A33172E9544F6F157DEA0BB46E2E" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_B5F3FCA31BAB2408E2E07DEA0BB5E5AC_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_B5F3FCA31BAB2408E2E07DEA0BB5E5AC" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_B1C4A33172E9544F6F157DEA0BB46E2E" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_B5F3FCA31BAB2408E2E07DEA0BB5E5AC" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_LongTermDebt" xlink:label="loc_us-gaap_LongTermDebt_110A16C431C95BCA02CE7DEA0BB58375" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2BD04E34EF51AB119A607DEA0BB5CCE5" xlink:to="loc_us-gaap_LongTermDebt_110A16C431C95BCA02CE7DEA0BB58375" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_CapitalLeaseObligations" xlink:label="loc_us-gaap_CapitalLeaseObligations_F74EDD3C67257671CBC57DEA0BB59A48" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2BD04E34EF51AB119A607DEA0BB5CCE5" xlink:to="loc_us-gaap_CapitalLeaseObligations_F74EDD3C67257671CBC57DEA0BB59A48" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_OtherBorrowings" xlink:label="loc_us-gaap_OtherBorrowings_77A2DA89AB61B2E503E67DEA0BB5B1FF" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2BD04E34EF51AB119A607DEA0BB5CCE5" xlink:to="loc_us-gaap_OtherBorrowings_77A2DA89AB61B2E503E67DEA0BB5B1FF" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DebtAndCapitalLeaseObligations" xlink:label="loc_us-gaap_DebtAndCapitalLeaseObligations_8B94410EF09B8456DF257DEA0BB5A003" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2BD04E34EF51AB119A607DEA0BB5CCE5" xlink:to="loc_us-gaap_DebtAndCapitalLeaseObligations_8B94410EF09B8456DF257DEA0BB5A003" xlink:type="arc" />
    <loc xlink:href="eme-20140630.xsd#eme_CurrentMaturitiesOfLongTermDebtAndCapitalLeaseObligations" xlink:label="loc_eme_CurrentMaturitiesOfLongTermDebtAndCapitalLeaseObligations_9F2E401CAEF1C2BDA0C87DEA0BB5381A" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2BD04E34EF51AB119A607DEA0BB5CCE5" xlink:to="loc_eme_CurrentMaturitiesOfLongTermDebtAndCapitalLeaseObligations_9F2E401CAEF1C2BDA0C87DEA0BB5381A" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_LongTermDebtAndCapitalLeaseObligations" xlink:label="loc_us-gaap_LongTermDebtAndCapitalLeaseObligations_0EF53823E514C67DA5C17DEA0BB57A39" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2BD04E34EF51AB119A607DEA0BB5CCE5" xlink:to="loc_us-gaap_LongTermDebtAndCapitalLeaseObligations_0EF53823E514C67DA5C17DEA0BB57A39" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.emcorgroup.com/role/DebtTables" xlink:type="extended" />
  <definitionLink xlink:role="http://www.emcorgroup.com/role/DispositionOfAssets" xlink:type="extended" />
  <definitionLink xlink:role="http://www.emcorgroup.com/role/DispositionOfAssetsNarrativeDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_0A3AF8399E5B8950A45BDEBBCDD36C4D" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_95BBF1A0444C43FBEF2ADEBBCDD35B6F" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_0A3AF8399E5B8950A45BDEBBCDD36C4D" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_95BBF1A0444C43FBEF2ADEBBCDD35B6F" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_24CECE0DC3DE42934F1FDEBBCDD32F36" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_95BBF1A0444C43FBEF2ADEBBCDD35B6F" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_24CECE0DC3DE42934F1FDEBBCDD32F36" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_6FA3703CEC38E7284E65DEBBCDD38A77_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_24CECE0DC3DE42934F1FDEBBCDD32F36" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_6FA3703CEC38E7284E65DEBBCDD38A77_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_6FA3703CEC38E7284E65DEBBCDD38A77" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_24CECE0DC3DE42934F1FDEBBCDD32F36" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_6FA3703CEC38E7284E65DEBBCDD38A77" xlink:type="arc" />
    <loc xlink:href="eme-20140630.xsd#eme_UnitedStatesBuildingServicesMember" xlink:label="loc_eme_UnitedStatesBuildingServicesMember_6C671D67CB882D04621BDEBBCDD3E993" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_6FA3703CEC38E7284E65DEBBCDD38A77" xlink:to="loc_eme_UnitedStatesBuildingServicesMember_6C671D67CB882D04621BDEBBCDD3E993" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ProceedsFromDivestitureOfBusinesses" xlink:label="loc_us-gaap_ProceedsFromDivestitureOfBusinesses_E39BD00F2C41B9BF39A3DEBBCDD3120E" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_0A3AF8399E5B8950A45BDEBBCDD36C4D" xlink:to="loc_us-gaap_ProceedsFromDivestitureOfBusinesses_E39BD00F2C41B9BF39A3DEBBCDD3120E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_GainLossOnSaleOfBusiness" xlink:label="loc_us-gaap_GainLossOnSaleOfBusiness_75E27E5464C008E1DAFEDEBBCDD3755A" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_0A3AF8399E5B8950A45BDEBBCDD36C4D" xlink:to="loc_us-gaap_GainLossOnSaleOfBusiness_75E27E5464C008E1DAFEDEBBCDD3755A" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.emcorgroup.com/role/DocumentAndEntityInformation" xlink:type="extended" />
  <definitionLink xlink:role="http://www.emcorgroup.com/role/EarningsPerShare" xlink:type="extended" />
  <definitionLink xlink:role="http://www.emcorgroup.com/role/EarningsPerShareDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_C627DA0C009A65B450E17DECFFB237B2" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable" xlink:label="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_6D4758044C481376E4087DECFFB2CBD7" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_C627DA0C009A65B450E17DECFFB237B2" xlink:to="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_6D4758044C481376E4087DECFFB2CBD7" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_9D719CB5CDB13AC7C8E87DECFFB2C1F2" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_6D4758044C481376E4087DECFFB2CBD7" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_9D719CB5CDB13AC7C8E87DECFFB2C1F2" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AntidilutiveSecuritiesNameDomain" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_9FFBAEF8A0640C4820E17DECFFB23B72_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_9D719CB5CDB13AC7C8E87DECFFB2C1F2" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_9FFBAEF8A0640C4820E17DECFFB23B72_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AntidilutiveSecuritiesNameDomain" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_9FFBAEF8A0640C4820E17DECFFB23B72" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_9D719CB5CDB13AC7C8E87DECFFB2C1F2" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_9FFBAEF8A0640C4820E17DECFFB23B72" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_7CAC877DDC434EEA644B7DECFFB20524" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_C627DA0C009A65B450E17DECFFB237B2" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_7CAC877DDC434EEA644B7DECFFB20524" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.emcorgroup.com/role/EarningsPerShareTables" xlink:type="extended" />
  <definitionLink xlink:role="http://www.emcorgroup.com/role/FairValueMeasurements" xlink:type="extended" />
  <definitionLink xlink:role="http://www.emcorgroup.com/role/FairValueMeasurementsPolicy" xlink:type="extended" />
  <definitionLink xlink:role="http://www.emcorgroup.com/role/FairValueMeasurementsScheduleOfAssetsAndLiabilitiesCarriedAtFairValueMeasuredOnRecurringBasisDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_1E7A792AE31E4D2ACEB75933C06BB769" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_6AA9D394A23EBA72BD715933C06A07B0" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_1E7A792AE31E4D2ACEB75933C06BB769" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_6AA9D394A23EBA72BD715933C06A07B0" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_CashAndCashEquivalentsAxis" xlink:label="loc_us-gaap_CashAndCashEquivalentsAxis_D38FA527FACE71C399A65933C06ACC2E" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_6AA9D394A23EBA72BD715933C06A07B0" xlink:to="loc_us-gaap_CashAndCashEquivalentsAxis_D38FA527FACE71C399A65933C06ACC2E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_A075589E1C4CB4508C185933C06A1E15_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CashAndCashEquivalentsAxis_D38FA527FACE71C399A65933C06ACC2E" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_A075589E1C4CB4508C185933C06A1E15_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_A075589E1C4CB4508C185933C06A1E15" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CashAndCashEquivalentsAxis_D38FA527FACE71C399A65933C06ACC2E" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_A075589E1C4CB4508C185933C06A1E15" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_MoneyMarketFundsMember" xlink:label="loc_us-gaap_MoneyMarketFundsMember_B0002D3A2F54287164CA5933C06A871A" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_A075589E1C4CB4508C185933C06A1E15" xlink:to="loc_us-gaap_MoneyMarketFundsMember_B0002D3A2F54287164CA5933C06A871A" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueByMeasurementBasisAxis" xlink:label="loc_us-gaap_FairValueByMeasurementBasisAxis_FA15B6856DC70C0F8E505933C06A9BD2" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_6AA9D394A23EBA72BD715933C06A07B0" xlink:to="loc_us-gaap_FairValueByMeasurementBasisAxis_FA15B6856DC70C0F8E505933C06A9BD2" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_698B3E248C108E2275EC5933C06A7506_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_FA15B6856DC70C0F8E505933C06A9BD2" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_698B3E248C108E2275EC5933C06A7506_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueDisclosureItemAmountsDomain" xlink:label="loc_us-gaap_FairValueDisclosureItemAmountsDomain_32CD34CB39B78A6A31115933C06A2B89" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_FA15B6856DC70C0F8E505933C06A9BD2" xlink:to="loc_us-gaap_FairValueDisclosureItemAmountsDomain_32CD34CB39B78A6A31115933C06A2B89" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_698B3E248C108E2275EC5933C06A7506" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_32CD34CB39B78A6A31115933C06A2B89" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_698B3E248C108E2275EC5933C06A7506" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueByMeasurementFrequencyAxis" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_D642EFB64E77548B61875933C06BC95D" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_6AA9D394A23EBA72BD715933C06A07B0" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_D642EFB64E77548B61875933C06BC95D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_5674156A34ACA37B3F705933C06B4EB5_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_D642EFB64E77548B61875933C06BC95D" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_5674156A34ACA37B3F705933C06B4EB5_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_5674156A34ACA37B3F705933C06B4EB5" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_D642EFB64E77548B61875933C06BC95D" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_5674156A34ACA37B3F705933C06B4EB5" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueMeasurementsRecurringMember" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_3E6707C986178EA8AEC65933C06BE4F9" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_5674156A34ACA37B3F705933C06B4EB5" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_3E6707C986178EA8AEC65933C06BE4F9" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_CA42294A926B50A2DA665933C06B05E2" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_6AA9D394A23EBA72BD715933C06A07B0" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_CA42294A926B50A2DA665933C06B05E2" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_BBF07D0B588A2EC865665933C06BA98C_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_CA42294A926B50A2DA665933C06B05E2" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_BBF07D0B588A2EC865665933C06BA98C_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_BBF07D0B588A2EC865665933C06BA98C" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_CA42294A926B50A2DA665933C06B05E2" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_BBF07D0B588A2EC865665933C06BA98C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueInputsLevel1Member" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_7B856729503978B30F285933C06BCF22" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_BBF07D0B588A2EC865665933C06BA98C" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_7B856729503978B30F285933C06BCF22" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueInputsLevel2Member" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_B544D88147C2995E85455933C06B4856" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_BBF07D0B588A2EC865665933C06BA98C" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_B544D88147C2995E85455933C06B4856" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FairValueInputsLevel3Member" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_A77A7363F058427E1EC35933C06BC899" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_BBF07D0B588A2EC865665933C06BA98C" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_A77A7363F058427E1EC35933C06BC899" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_CashAndCashEquivalentsFairValueDisclosure" xlink:label="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_6D79E173FDDF49233BEB5933C06BD931" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_1E7A792AE31E4D2ACEB75933C06BB769" xlink:to="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_6D79E173FDDF49233BEB5933C06BD931" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_RestrictedCashAndCashEquivalentsAtCarryingValue" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsAtCarryingValue_4147B56CA86F56CFC4C25933C06C56E8" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_1E7A792AE31E4D2ACEB75933C06BB769" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsAtCarryingValue_4147B56CA86F56CFC4C25933C06C56E8" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_AssetsFairValueDisclosureRecurring" xlink:label="loc_us-gaap_AssetsFairValueDisclosureRecurring_33B3A5F4B6BCA5BADDBD5933C06C744A" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_1E7A792AE31E4D2ACEB75933C06BB769" xlink:to="loc_us-gaap_AssetsFairValueDisclosureRecurring_33B3A5F4B6BCA5BADDBD5933C06C744A" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.emcorgroup.com/role/FairValueMeasurementsTables" xlink:type="extended" />
  <definitionLink xlink:role="http://www.emcorgroup.com/role/IncomeTaxes" xlink:type="extended" />
  <definitionLink xlink:role="http://www.emcorgroup.com/role/IncomeTaxesDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_OperatingLossCarryforwardsLineItems" xlink:label="loc_us-gaap_OperatingLossCarryforwardsLineItems_CE4BB173FFCCD31914D36D97FEAEDF97" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_OperatingLossCarryforwardsTable" xlink:label="loc_us-gaap_OperatingLossCarryforwardsTable_C4247DE0496F5EB738DB6D97FEAEAA0E" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_CE4BB173FFCCD31914D36D97FEAEDF97" xlink:to="loc_us-gaap_OperatingLossCarryforwardsTable_C4247DE0496F5EB738DB6D97FEAEAA0E" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_IncomeTaxAuthorityAxis" xlink:label="loc_us-gaap_IncomeTaxAuthorityAxis_59E206755BD4354538A36D97FEAE1962" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OperatingLossCarryforwardsTable_C4247DE0496F5EB738DB6D97FEAEAA0E" xlink:to="loc_us-gaap_IncomeTaxAuthorityAxis_59E206755BD4354538A36D97FEAE1962" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_IncomeTaxAuthorityDomain" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_CEA36B1D1FD267BE69B16D97FEAE823A_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_59E206755BD4354538A36D97FEAE1962" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_CEA36B1D1FD267BE69B16D97FEAE823A_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_IncomeTaxAuthorityDomain" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_CEA36B1D1FD267BE69B16D97FEAE823A" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_59E206755BD4354538A36D97FEAE1962" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_CEA36B1D1FD267BE69B16D97FEAE823A" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.emcorgroup.com/role/Inventories" xlink:type="extended" />
  <definitionLink xlink:role="http://www.emcorgroup.com/role/InventoriesInventoriesDetails" xlink:type="extended" />
  <definitionLink xlink:role="http://www.emcorgroup.com/role/InventoriesTables" xlink:type="extended" />
  <definitionLink xlink:role="http://www.emcorgroup.com/role/NewAccountingPronouncements" xlink:type="extended" />
  <definitionLink xlink:role="http://www.emcorgroup.com/role/RetirementPlans" xlink:type="extended" />
  <definitionLink xlink:role="http://www.emcorgroup.com/role/RetirementPlansComponentsOfNetPeriodicPensionBenefitCostDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_37E16EDF7DC9B4A38F63DEBBCE08DAC9" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_59728D488F460DD57187DEBBCE080A96" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_37E16EDF7DC9B4A38F63DEBBCE08DAC9" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_59728D488F460DD57187DEBBCE080A96" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_LegalEntityAxis" xlink:label="loc_dei_LegalEntityAxis_0BA083C615690B632305DEBBCE081F2D" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_59728D488F460DD57187DEBBCE080A96" xlink:to="loc_dei_LegalEntityAxis_0BA083C615690B632305DEBBCE081F2D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_EntityDomain" xlink:label="loc_dei_EntityDomain_9D8BE9D3C45902792943DEBBCE083956_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_0BA083C615690B632305DEBBCE081F2D" xlink:to="loc_dei_EntityDomain_9D8BE9D3C45902792943DEBBCE083956_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_EntityDomain" xlink:label="loc_dei_EntityDomain_9D8BE9D3C45902792943DEBBCE083956" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_0BA083C615690B632305DEBBCE081F2D" xlink:to="loc_dei_EntityDomain_9D8BE9D3C45902792943DEBBCE083956" xlink:type="arc" />
    <loc xlink:href="eme-20140630.xsd#eme_UnitedKingdomSubsidiaryMember" xlink:label="loc_eme_UnitedKingdomSubsidiaryMember_B8EE7AA19F0F9947BF49DEBBCE080EE8" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_9D8BE9D3C45902792943DEBBCE083956" xlink:to="loc_eme_UnitedKingdomSubsidiaryMember_B8EE7AA19F0F9947BF49DEBBCE080EE8" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis" xlink:label="loc_us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis_C0BEA3D7A4BC385CFDC1DEBBCE08D462" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_59728D488F460DD57187DEBBCE080A96" xlink:to="loc_us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis_C0BEA3D7A4BC385CFDC1DEBBCE08D462" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DefinedBenefitPlansDomain" xlink:label="loc_us-gaap_DefinedBenefitPlansDomain_D564314A05A5D565C570DEBBCE08499B_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis_C0BEA3D7A4BC385CFDC1DEBBCE08D462" xlink:to="loc_us-gaap_DefinedBenefitPlansDomain_D564314A05A5D565C570DEBBCE08499B_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DefinedBenefitPlansDomain" xlink:label="loc_us-gaap_DefinedBenefitPlansDomain_D564314A05A5D565C570DEBBCE08499B" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis_C0BEA3D7A4BC385CFDC1DEBBCE08D462" xlink:to="loc_us-gaap_DefinedBenefitPlansDomain_D564314A05A5D565C570DEBBCE08499B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ForeignPensionPlansDefinedBenefitMember" xlink:label="loc_us-gaap_ForeignPensionPlansDefinedBenefitMember_E7E6112D4F0D1954432BDEBBCE0889F7" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlansDomain_D564314A05A5D565C570DEBBCE08499B" xlink:to="loc_us-gaap_ForeignPensionPlansDefinedBenefitMember_E7E6112D4F0D1954432BDEBBCE0889F7" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DefinedBenefitPlanInterestCost" xlink:label="loc_us-gaap_DefinedBenefitPlanInterestCost_3030C869C354BC7A9333DEBBCE0956E1" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_37E16EDF7DC9B4A38F63DEBBCE08DAC9" xlink:to="loc_us-gaap_DefinedBenefitPlanInterestCost_3030C869C354BC7A9333DEBBCE0956E1" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets" xlink:label="loc_us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets_BE14BDCEF23FA668C4FEDEBBCE096DBA" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_37E16EDF7DC9B4A38F63DEBBCE08DAC9" xlink:to="loc_us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets_BE14BDCEF23FA668C4FEDEBBCE096DBA" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DefinedBenefitPlanFutureAmortizationOfGainLoss" xlink:label="loc_us-gaap_DefinedBenefitPlanFutureAmortizationOfGainLoss_F96793D1F383C29ED4A3DEBBCE094DEE" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_37E16EDF7DC9B4A38F63DEBBCE08DAC9" xlink:to="loc_us-gaap_DefinedBenefitPlanFutureAmortizationOfGainLoss_F96793D1F383C29ED4A3DEBBCE094DEE" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost" xlink:label="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_CF603A8C2FA1A21649C4DEBBCE09EB54" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_37E16EDF7DC9B4A38F63DEBBCE08DAC9" xlink:to="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_CF603A8C2FA1A21649C4DEBBCE09EB54" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.emcorgroup.com/role/RetirementPlansNarrativeDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_3551E56B43962B246612DEBBCDF42DF5" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_691272EABA24537AA420DEBBCDF46AC1" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_3551E56B43962B246612DEBBCDF42DF5" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_691272EABA24537AA420DEBBCDF46AC1" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_LegalEntityAxis" xlink:label="loc_dei_LegalEntityAxis_E676CD82144BDFF82740DEBBCDF47AA4" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_691272EABA24537AA420DEBBCDF46AC1" xlink:to="loc_dei_LegalEntityAxis_E676CD82144BDFF82740DEBBCDF47AA4" xlink:type="arc" />
    <loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_EntityDomain" xlink:label="loc_dei_EntityDomain_2BF814530E3356BC2919DEBBCDF4ACF5_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_E676CD82144BDFF82740DEBBCDF47AA4" xlink:to="loc_dei_EntityDomain_2BF814530E3356BC2919DEBBCDF4ACF5_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_EntityDomain" xlink:label="loc_dei_EntityDomain_2BF814530E3356BC2919DEBBCDF4ACF5" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_E676CD82144BDFF82740DEBBCDF47AA4" xlink:to="loc_dei_EntityDomain_2BF814530E3356BC2919DEBBCDF4ACF5" xlink:type="arc" />
    <loc xlink:href="eme-20140630.xsd#eme_UnitedKingdomSubsidiaryMember" xlink:label="loc_eme_UnitedKingdomSubsidiaryMember_4CDB920B279E9D364775DEBBCDF42E5F" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_2BF814530E3356BC2919DEBBCDF4ACF5" xlink:to="loc_eme_UnitedKingdomSubsidiaryMember_4CDB920B279E9D364775DEBBCDF42E5F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis" xlink:label="loc_us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis_D1020E3419C039A5B81ADEBBCDF4290F" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_691272EABA24537AA420DEBBCDF46AC1" xlink:to="loc_us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis_D1020E3419C039A5B81ADEBBCDF4290F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DefinedBenefitPlansDomain" xlink:label="loc_us-gaap_DefinedBenefitPlansDomain_8250FF2ECDFF4A1E0CFDDEBBCDF43239_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis_D1020E3419C039A5B81ADEBBCDF4290F" xlink:to="loc_us-gaap_DefinedBenefitPlansDomain_8250FF2ECDFF4A1E0CFDDEBBCDF43239_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DefinedBenefitPlansDomain" xlink:label="loc_us-gaap_DefinedBenefitPlansDomain_8250FF2ECDFF4A1E0CFDDEBBCDF43239" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis_D1020E3419C039A5B81ADEBBCDF4290F" xlink:to="loc_us-gaap_DefinedBenefitPlansDomain_8250FF2ECDFF4A1E0CFDDEBBCDF43239" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ForeignPensionPlansDefinedBenefitMember" xlink:label="loc_us-gaap_ForeignPensionPlansDefinedBenefitMember_94A024025D5CE7760B79DEBBCDF4B7C1" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlansDomain_8250FF2ECDFF4A1E0CFDDEBBCDF43239" xlink:to="loc_us-gaap_ForeignPensionPlansDefinedBenefitMember_94A024025D5CE7760B79DEBBCDF4B7C1" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DefinedBenefitPlanContributionsByEmployer" xlink:label="loc_us-gaap_DefinedBenefitPlanContributionsByEmployer_98413CA6CE911DC6AD21DEBBCDF45FEA" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_3551E56B43962B246612DEBBCDF42DF5" xlink:to="loc_us-gaap_DefinedBenefitPlanContributionsByEmployer_98413CA6CE911DC6AD21DEBBCDF45FEA" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_DefinedBenefitPlansEstimatedFutureEmployerContributionsInCurrentFiscalYear" xlink:label="loc_us-gaap_DefinedBenefitPlansEstimatedFutureEmployerContributionsInCurrentFiscalYear_0D713ACF115AB41BBB64DEBBCDF51A8F" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_3551E56B43962B246612DEBBCDF42DF5" xlink:to="loc_us-gaap_DefinedBenefitPlansEstimatedFutureEmployerContributionsInCurrentFiscalYear_0D713ACF115AB41BBB64DEBBCDF51A8F" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.emcorgroup.com/role/RetirementPlansTables" xlink:type="extended" />
  <definitionLink xlink:role="http://www.emcorgroup.com/role/ScheduleOfRestructuringActivitiesDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_RestructuringCostAndReserveLineItems" xlink:label="loc_us-gaap_RestructuringCostAndReserveLineItems_58874DEACB382D5A01E0652019585BA0" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable" xlink:label="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_FD0A75552687EE49E35065201958B5CA" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_58874DEACB382D5A01E0652019585BA0" xlink:to="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_FD0A75552687EE49E35065201958B5CA" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StatementGeographicalAxis" xlink:label="loc_us-gaap_StatementGeographicalAxis_572A0FF689CCECE7B72B652E331C22E4" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_FD0A75552687EE49E35065201958B5CA" xlink:to="loc_us-gaap_StatementGeographicalAxis_572A0FF689CCECE7B72B652E331C22E4" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_SegmentGeographicalDomain" xlink:label="loc_us-gaap_SegmentGeographicalDomain_C577C6DE48AA29CB2FE8652E33DA60CF_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementGeographicalAxis_572A0FF689CCECE7B72B652E331C22E4" xlink:to="loc_us-gaap_SegmentGeographicalDomain_C577C6DE48AA29CB2FE8652E33DA60CF_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_SegmentGeographicalDomain" xlink:label="loc_us-gaap_SegmentGeographicalDomain_C577C6DE48AA29CB2FE8652E33DA60CF" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementGeographicalAxis_572A0FF689CCECE7B72B652E331C22E4" xlink:to="loc_us-gaap_SegmentGeographicalDomain_C577C6DE48AA29CB2FE8652E33DA60CF" xlink:type="arc" />
    <loc xlink:href="http://xbrl.sec.gov/country/2013/country-2013-01-31.xsd#country_GB" xlink:label="loc_country_GB_8821E2E79BE90ACCAB6E652EA2C03FFF" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentGeographicalDomain_C577C6DE48AA29CB2FE8652E33DA60CF" xlink:to="loc_country_GB_8821E2E79BE90ACCAB6E652EA2C03FFF" xlink:type="arc" />
    <loc xlink:href="http://xbrl.sec.gov/country/2013/country-2013-01-31.xsd#country_US" xlink:label="loc_country_US_DA5AD4D80C3E2708377E652F3E92F9C0" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentGeographicalDomain_C577C6DE48AA29CB2FE8652E33DA60CF" xlink:to="loc_country_US_DA5AD4D80C3E2708377E652F3E92F9C0" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ConsolidationItemsAxis" xlink:label="loc_us-gaap_ConsolidationItemsAxis_88D298BDA8A3BE8C8E896521C3C2CB94" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_FD0A75552687EE49E35065201958B5CA" xlink:to="loc_us-gaap_ConsolidationItemsAxis_88D298BDA8A3BE8C8E896521C3C2CB94" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ConsolidationItemsDomain" xlink:label="loc_us-gaap_ConsolidationItemsDomain_9F80122168CFEFB1D5C76521C440D2BE_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConsolidationItemsAxis_88D298BDA8A3BE8C8E896521C3C2CB94" xlink:to="loc_us-gaap_ConsolidationItemsDomain_9F80122168CFEFB1D5C76521C440D2BE_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ConsolidationItemsDomain" xlink:label="loc_us-gaap_ConsolidationItemsDomain_9F80122168CFEFB1D5C76521C440D2BE" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConsolidationItemsAxis_88D298BDA8A3BE8C8E896521C3C2CB94" xlink:to="loc_us-gaap_ConsolidationItemsDomain_9F80122168CFEFB1D5C76521C440D2BE" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_OperatingSegmentsMember" xlink:label="loc_us-gaap_OperatingSegmentsMember_94E8B7F10C5261E6E610652623A8A49B" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConsolidationItemsDomain_9F80122168CFEFB1D5C76521C440D2BE" xlink:to="loc_us-gaap_OperatingSegmentsMember_94E8B7F10C5261E6E610652623A8A49B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_CorporateNonSegmentMember" xlink:label="loc_us-gaap_CorporateNonSegmentMember_9448E5B8048FE163FEB9652287A45887" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConsolidationItemsDomain_9F80122168CFEFB1D5C76521C440D2BE" xlink:to="loc_us-gaap_CorporateNonSegmentMember_9448E5B8048FE163FEB9652287A45887" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_RestructuringCostAndReserveAxis" xlink:label="loc_us-gaap_RestructuringCostAndReserveAxis_D9C626366CE0250D3F4C65201958AEBE" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_FD0A75552687EE49E35065201958B5CA" xlink:to="loc_us-gaap_RestructuringCostAndReserveAxis_D9C626366CE0250D3F4C65201958AEBE" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_TypeOfRestructuringDomain" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_BC91DCE692A8B93E747F6520195836B5_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_D9C626366CE0250D3F4C65201958AEBE" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_BC91DCE692A8B93E747F6520195836B5_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_TypeOfRestructuringDomain" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_BC91DCE692A8B93E747F6520195836B5" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_D9C626366CE0250D3F4C65201958AEBE" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_BC91DCE692A8B93E747F6520195836B5" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_EmployeeSeveranceMember" xlink:label="loc_us-gaap_EmployeeSeveranceMember_0FB186BCF5BDAFDDB88B6520195835C8" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_BC91DCE692A8B93E747F6520195836B5" xlink:to="loc_us-gaap_EmployeeSeveranceMember_0FB186BCF5BDAFDDB88B6520195835C8" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_FacilityClosingMember" xlink:label="loc_us-gaap_FacilityClosingMember_867E864F20203E3CD70F6520195854FF" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_BC91DCE692A8B93E747F6520195836B5" xlink:to="loc_us-gaap_FacilityClosingMember_867E864F20203E3CD70F6520195854FF" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_7256FE759EEED4221B38652019584D9F" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_FD0A75552687EE49E35065201958B5CA" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_7256FE759EEED4221B38652019584D9F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_E3CD2F291046A7BDC86465201958E336_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_7256FE759EEED4221B38652019584D9F" xlink:to="loc_us-gaap_SegmentDomain_E3CD2F291046A7BDC86465201958E336_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_E3CD2F291046A7BDC86465201958E336" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_7256FE759EEED4221B38652019584D9F" xlink:to="loc_us-gaap_SegmentDomain_E3CD2F291046A7BDC86465201958E336" xlink:type="arc" />
    <loc xlink:href="eme-20140630.xsd#eme_UnitedStatesElectricalConstructionAndFacilitiesServicesMember" xlink:label="loc_eme_UnitedStatesElectricalConstructionAndFacilitiesServicesMember_C8C09A8EEC5FC08A74AC652019582932" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_E3CD2F291046A7BDC86465201958E336" xlink:to="loc_eme_UnitedStatesElectricalConstructionAndFacilitiesServicesMember_C8C09A8EEC5FC08A74AC652019582932" xlink:type="arc" />
    <loc xlink:href="eme-20140630.xsd#eme_UnitedStatesMechanicalConstructionAndFacilitiesServicesMember" xlink:label="loc_eme_UnitedStatesMechanicalConstructionAndFacilitiesServicesMember_72EEBF8055199E5E6ED56520195825FC" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_E3CD2F291046A7BDC86465201958E336" xlink:to="loc_eme_UnitedStatesMechanicalConstructionAndFacilitiesServicesMember_72EEBF8055199E5E6ED56520195825FC" xlink:type="arc" />
    <loc xlink:href="eme-20140630.xsd#eme_UnitedStatesBuildingServicesMember" xlink:label="loc_eme_UnitedStatesBuildingServicesMember_7FC7DBA78E50B17B0C4665201958C778" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_E3CD2F291046A7BDC86465201958E336" xlink:to="loc_eme_UnitedStatesBuildingServicesMember_7FC7DBA78E50B17B0C4665201958C778" xlink:type="arc" />
    <loc xlink:href="eme-20140630.xsd#eme_UnitedKingdomConstructionAndBuildingServicesMember" xlink:label="loc_eme_UnitedKingdomConstructionAndBuildingServicesMember_E38DF85B4ED9572ABEB165201958DD9B" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_E3CD2F291046A7BDC86465201958E336" xlink:to="loc_eme_UnitedKingdomConstructionAndBuildingServicesMember_E38DF85B4ED9572ABEB165201958DD9B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_CorporateNonSegmentMember" xlink:label="loc_us-gaap_CorporateNonSegmentMember_3503F0B103854C1ECD9765201958E930" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_E3CD2F291046A7BDC86465201958E336" xlink:to="loc_us-gaap_CorporateNonSegmentMember_3503F0B103854C1ECD9765201958E930" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_RestructuringReserve" xlink:label="loc_us-gaap_RestructuringReserve_200CA093B1F1D69242B0652019587C3A" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_58874DEACB382D5A01E0652019585BA0" xlink:to="loc_us-gaap_RestructuringReserve_200CA093B1F1D69242B0652019587C3A" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_RestructuringCharges" xlink:label="loc_us-gaap_RestructuringCharges_F33A32BD74BFABB0AD3C65201959AF8F" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_58874DEACB382D5A01E0652019585BA0" xlink:to="loc_us-gaap_RestructuringCharges_F33A32BD74BFABB0AD3C65201959AF8F" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_PaymentsForRestructuring" xlink:label="loc_us-gaap_PaymentsForRestructuring_A7E10087419EABF449D165201959BCAE" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_58874DEACB382D5A01E0652019585BA0" xlink:to="loc_us-gaap_PaymentsForRestructuring_A7E10087419EABF449D165201959BCAE" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.emcorgroup.com/role/SegmentInformation" xlink:type="extended" />
  <definitionLink xlink:role="http://www.emcorgroup.com/role/SegmentInformationInformationAboutIndustrySegmentsAndGeographicAreasDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_SegmentReportingInformationLineItems" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_18DC7F5CDE4987428E177D291E4504B6" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_77AEC72F51EB80D58CBB7D291E4458D8" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_18DC7F5CDE4987428E177D291E4504B6" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_77AEC72F51EB80D58CBB7D291E4458D8" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_LegalEntityAxis" xlink:label="loc_dei_LegalEntityAxis_35BFA1599142F68A771A7D291E44EE40" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_77AEC72F51EB80D58CBB7D291E4458D8" xlink:to="loc_dei_LegalEntityAxis_35BFA1599142F68A771A7D291E44EE40" xlink:type="arc" />
    <loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_EntityDomain" xlink:label="loc_dei_EntityDomain_F78868E408CC9C93E1547D291E44712E_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_35BFA1599142F68A771A7D291E44EE40" xlink:to="loc_dei_EntityDomain_F78868E408CC9C93E1547D291E44712E_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_EntityDomain" xlink:label="loc_dei_EntityDomain_F78868E408CC9C93E1547D291E44712E" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_35BFA1599142F68A771A7D291E44EE40" xlink:to="loc_dei_EntityDomain_F78868E408CC9C93E1547D291E44712E" xlink:type="arc" />
    <loc xlink:href="eme-20140630.xsd#eme_UnitedKingdomSubsidiaryMember" xlink:label="loc_eme_UnitedKingdomSubsidiaryMember_B1DA33C78A10453FC6F77D291E44518D" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_F78868E408CC9C93E1547D291E44712E" xlink:to="loc_eme_UnitedKingdomSubsidiaryMember_B1DA33C78A10453FC6F77D291E44518D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StatementGeographicalAxis" xlink:label="loc_us-gaap_StatementGeographicalAxis_D7DE5B0AA8B15C114AC17D291E44013A" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_77AEC72F51EB80D58CBB7D291E4458D8" xlink:to="loc_us-gaap_StatementGeographicalAxis_D7DE5B0AA8B15C114AC17D291E44013A" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_SegmentGeographicalDomain" xlink:label="loc_us-gaap_SegmentGeographicalDomain_58ABD51B5F4F212C8F477D291E440349_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementGeographicalAxis_D7DE5B0AA8B15C114AC17D291E44013A" xlink:to="loc_us-gaap_SegmentGeographicalDomain_58ABD51B5F4F212C8F477D291E440349_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_SegmentGeographicalDomain" xlink:label="loc_us-gaap_SegmentGeographicalDomain_58ABD51B5F4F212C8F477D291E440349" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementGeographicalAxis_D7DE5B0AA8B15C114AC17D291E44013A" xlink:to="loc_us-gaap_SegmentGeographicalDomain_58ABD51B5F4F212C8F477D291E440349" xlink:type="arc" />
    <loc xlink:href="http://xbrl.sec.gov/country/2013/country-2013-01-31.xsd#country_US" xlink:label="loc_country_US_A213B4D3D82D9628B27F7D291E448DEE" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentGeographicalDomain_58ABD51B5F4F212C8F477D291E440349" xlink:to="loc_country_US_A213B4D3D82D9628B27F7D291E448DEE" xlink:type="arc" />
    <loc xlink:href="http://xbrl.sec.gov/country/2013/country-2013-01-31.xsd#country_GB" xlink:label="loc_country_GB_FBC791C4D91D0D062C387D291E44AE8B" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentGeographicalDomain_58ABD51B5F4F212C8F477D291E440349" xlink:to="loc_country_GB_FBC791C4D91D0D062C387D291E44AE8B" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ConsolidationItemsAxis" xlink:label="loc_us-gaap_ConsolidationItemsAxis_CD09B35C740BCA9B95CD7D291E44336D" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_77AEC72F51EB80D58CBB7D291E4458D8" xlink:to="loc_us-gaap_ConsolidationItemsAxis_CD09B35C740BCA9B95CD7D291E44336D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ConsolidationItemsDomain" xlink:label="loc_us-gaap_ConsolidationItemsDomain_BF8934F3AC70BEA076CC7D291E44133E_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConsolidationItemsAxis_CD09B35C740BCA9B95CD7D291E44336D" xlink:to="loc_us-gaap_ConsolidationItemsDomain_BF8934F3AC70BEA076CC7D291E44133E_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_ConsolidationItemsDomain" xlink:label="loc_us-gaap_ConsolidationItemsDomain_BF8934F3AC70BEA076CC7D291E44133E" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConsolidationItemsAxis_CD09B35C740BCA9B95CD7D291E44336D" xlink:to="loc_us-gaap_ConsolidationItemsDomain_BF8934F3AC70BEA076CC7D291E44133E" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_OperatingSegmentsMember" xlink:label="loc_us-gaap_OperatingSegmentsMember_569EBF13DE76C420685A7D291E45D033" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConsolidationItemsDomain_BF8934F3AC70BEA076CC7D291E44133E" xlink:to="loc_us-gaap_OperatingSegmentsMember_569EBF13DE76C420685A7D291E45D033" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_IntersegmentEliminationMember" xlink:label="loc_us-gaap_IntersegmentEliminationMember_EBC9FE03F31F21AC059E7D291E45EBF5" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConsolidationItemsDomain_BF8934F3AC70BEA076CC7D291E44133E" xlink:to="loc_us-gaap_IntersegmentEliminationMember_EBC9FE03F31F21AC059E7D291E45EBF5" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_CorporateNonSegmentMember" xlink:label="loc_us-gaap_CorporateNonSegmentMember_C13B57BF960611924C0D7D291E45398D" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConsolidationItemsDomain_BF8934F3AC70BEA076CC7D291E44133E" xlink:to="loc_us-gaap_CorporateNonSegmentMember_C13B57BF960611924C0D7D291E45398D" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_16B0FFF589B624F4AB4F7D291E456D35" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_77AEC72F51EB80D58CBB7D291E4458D8" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_16B0FFF589B624F4AB4F7D291E456D35" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_063F08BBDE46B3F4930B7D291E452D17_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_16B0FFF589B624F4AB4F7D291E456D35" xlink:to="loc_us-gaap_SegmentDomain_063F08BBDE46B3F4930B7D291E452D17_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_063F08BBDE46B3F4930B7D291E452D17" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_16B0FFF589B624F4AB4F7D291E456D35" xlink:to="loc_us-gaap_SegmentDomain_063F08BBDE46B3F4930B7D291E452D17" xlink:type="arc" />
    <loc xlink:href="eme-20140630.xsd#eme_UnitedStatesElectricalConstructionAndFacilitiesServicesMember" xlink:label="loc_eme_UnitedStatesElectricalConstructionAndFacilitiesServicesMember_0524D0FAD05D0EEB8F057D291E45C2EB" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_063F08BBDE46B3F4930B7D291E452D17" xlink:to="loc_eme_UnitedStatesElectricalConstructionAndFacilitiesServicesMember_0524D0FAD05D0EEB8F057D291E45C2EB" xlink:type="arc" />
    <loc xlink:href="eme-20140630.xsd#eme_UnitedStatesMechanicalConstructionAndFacilitiesServicesMember" xlink:label="loc_eme_UnitedStatesMechanicalConstructionAndFacilitiesServicesMember_724AE18BD9AFA70F637D7D291E455BEB" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_063F08BBDE46B3F4930B7D291E452D17" xlink:to="loc_eme_UnitedStatesMechanicalConstructionAndFacilitiesServicesMember_724AE18BD9AFA70F637D7D291E455BEB" xlink:type="arc" />
    <loc xlink:href="eme-20140630.xsd#eme_UnitedStatesBuildingServicesMember" xlink:label="loc_eme_UnitedStatesBuildingServicesMember_870871ABECD3D6F0C9587D291E45AE1C" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_063F08BBDE46B3F4930B7D291E452D17" xlink:to="loc_eme_UnitedStatesBuildingServicesMember_870871ABECD3D6F0C9587D291E45AE1C" xlink:type="arc" />
    <loc xlink:href="eme-20140630.xsd#eme_UnitedStatesIndustrialServicesMember" xlink:label="loc_eme_UnitedStatesIndustrialServicesMember_A2540E0EFB1C69289A027D291E45BCDB" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_063F08BBDE46B3F4930B7D291E452D17" xlink:to="loc_eme_UnitedStatesIndustrialServicesMember_A2540E0EFB1C69289A027D291E45BCDB" xlink:type="arc" />
    <loc xlink:href="eme-20140630.xsd#eme_UnitedKingdomConstructionAndBuildingServicesMember" xlink:label="loc_eme_UnitedKingdomConstructionAndBuildingServicesMember_3F958152EC9B918EA68F7D291E45AAC5" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_063F08BBDE46B3F4930B7D291E452D17" xlink:to="loc_eme_UnitedKingdomConstructionAndBuildingServicesMember_3F958152EC9B918EA68F7D291E45AAC5" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_CorporateNonSegmentMember" xlink:label="loc_us-gaap_CorporateNonSegmentMember_EC2C43F0C43C820C232D7D291E45007C" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_063F08BBDE46B3F4930B7D291E452D17" xlink:to="loc_us-gaap_CorporateNonSegmentMember_EC2C43F0C43C820C232D7D291E45007C" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_SalesRevenueNet" xlink:label="loc_us-gaap_SalesRevenueNet_64EE4FD2AEF5CAA8C38C7D291E45E153" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_18DC7F5CDE4987428E177D291E4504B6" xlink:to="loc_us-gaap_SalesRevenueNet_64EE4FD2AEF5CAA8C38C7D291E45E153" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_Revenues" xlink:label="loc_us-gaap_Revenues_2703E7B0562A26A283DF7D291E451D4A" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_18DC7F5CDE4987428E177D291E4504B6" xlink:to="loc_us-gaap_Revenues_2703E7B0562A26A283DF7D291E451D4A" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_OperatingIncomeLoss" xlink:label="loc_us-gaap_OperatingIncomeLoss_78C83AED1BEBB177309F7D291E465B65" xlink:type="locator" />
    <definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_18DC7F5CDE4987428E177D291E4504B6" xlink:to="loc_us-gaap_OperatingIncomeLoss_78C83AED1BEBB177309F7D291E465B65" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_RestructuringCharges" xlink:label="loc_us-gaap_RestructuringCharges_1339BBACF0372336B92E7D291E4621DB" xlink:type="locator" />
    <definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_18DC7F5CDE4987428E177D291E4504B6" xlink:to="loc_us-gaap_RestructuringCharges_1339BBACF0372336B92E7D291E4621DB" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_InterestExpense" xlink:label="loc_us-gaap_InterestExpense_F8D45E2135593B818FF07D291E4613A5" xlink:type="locator" />
    <definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_18DC7F5CDE4987428E177D291E4504B6" xlink:to="loc_us-gaap_InterestExpense_F8D45E2135593B818FF07D291E4613A5" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_InvestmentIncomeInterest" xlink:label="loc_us-gaap_InvestmentIncomeInterest_574E950EEEEE0CFC55097D291E4679CE" xlink:type="locator" />
    <definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_18DC7F5CDE4987428E177D291E4504B6" xlink:to="loc_us-gaap_InvestmentIncomeInterest_574E950EEEEE0CFC55097D291E4679CE" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments_408188D397DB225F2A777D291E46D005" xlink:type="locator" />
    <definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_18DC7F5CDE4987428E177D291E4504B6" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments_408188D397DB225F2A777D291E46D005" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_Assets" xlink:label="loc_us-gaap_Assets_A2DF5F14131C04D68D647D291E46E8B1" xlink:type="locator" />
    <definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_18DC7F5CDE4987428E177D291E4504B6" xlink:to="loc_us-gaap_Assets_A2DF5F14131C04D68D647D291E46E8B1" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_InsuranceRecoveries" xlink:label="loc_us-gaap_InsuranceRecoveries_748F6F2ECC49437A4F787D291E469F90" xlink:type="locator" />
    <definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_18DC7F5CDE4987428E177D291E4504B6" xlink:to="loc_us-gaap_InsuranceRecoveries_748F6F2ECC49437A4F787D291E469F90" xlink:type="arc" />
    <loc xlink:href="eme-20140630.xsd#eme_IncomeFromReductionInEstimateOfCertainAccruedContractCosts" xlink:label="loc_eme_IncomeFromReductionInEstimateOfCertainAccruedContractCosts_A294FC01BA77FADA41E77D291E46FDF9" xlink:type="locator" />
    <definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_18DC7F5CDE4987428E177D291E4504B6" xlink:to="loc_eme_IncomeFromReductionInEstimateOfCertainAccruedContractCosts_A294FC01BA77FADA41E77D291E46FDF9" xlink:type="arc" />
  </definitionLink>
  <definitionLink xlink:role="http://www.emcorgroup.com/role/SegmentInformationTables" xlink:type="extended" />
  <definitionLink xlink:role="http://www.emcorgroup.com/role/SubsequentEventsSubsequentEvents" xlink:type="extended" />
  <definitionLink xlink:role="http://www.emcorgroup.com/role/SubsequentEventsSubsequentEventsDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_SubsequentEventLineItems" xlink:label="loc_us-gaap_SubsequentEventLineItems_9C401A9F264385937447653925704D0B" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_SubsequentEventTable" xlink:label="loc_us-gaap_SubsequentEventTable_27F9817A65DD4487BD0B65392570AC3C" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SubsequentEventLineItems_9C401A9F264385937447653925704D0B" xlink:to="loc_us-gaap_SubsequentEventTable_27F9817A65DD4487BD0B65392570AC3C" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_SubsequentEventTypeAxis" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_744856CEE11D5ED4CFF765392570D174" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_27F9817A65DD4487BD0B65392570AC3C" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_744856CEE11D5ED4CFF765392570D174" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_DC7722F3D1120BDF020A653925705FB2_default" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_744856CEE11D5ED4CFF765392570D174" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_DC7722F3D1120BDF020A653925705FB2_default" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_DC7722F3D1120BDF020A653925705FB2" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_744856CEE11D5ED4CFF765392570D174" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_DC7722F3D1120BDF020A653925705FB2" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_SubsequentEventMember" xlink:label="loc_us-gaap_SubsequentEventMember_98E68D233F7E9870D8AC653925702554" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_DC7722F3D1120BDF020A653925705FB2" xlink:to="loc_us-gaap_SubsequentEventMember_98E68D233F7E9870D8AC653925702554" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2014/elts/us-gaap-2014-01-31.xsd#us-gaap_SubsequentEventsDate" xlink:label="loc_us-gaap_SubsequentEventsDate_F5F89558715BFC42ACDA653925704EDE" xlink:type="locator" />
    <definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_9C401A9F264385937447653925704D0B" xlink:to="loc_us-gaap_SubsequentEventsDate_F5F89558715BFC42ACDA653925704EDE" xlink:type="arc" />
    <loc xlink:href="eme-20140630.xsd#eme_ExpectedGainOnSaleOfBuilding" xlink:label="loc_eme_ExpectedGainOnSaleOfBuilding_E4945C5127753328C293653925703138" xlink:type="locator" />
    <definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_9C401A9F264385937447653925704D0B" xlink:to="loc_eme_ExpectedGainOnSaleOfBuilding_E4945C5127753328C293653925703138" xlink:type="arc" />
  </definitionLink>
</linkbase>


