<?xml version="1.0" encoding="US-ASCII"?>
<!-- Generated by Fujitsu XWand B0126 -->
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:p0="http://xbrl.org/2005/xbrldt" xmlns:xbrli="http://www.xbrl.org/2003/instance" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:roleRef roleURI="http://eme.edison.com/role/StatementOfTotalEquity" xlink:href="eme-20091231.xsd#StatementOfEquity" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all" xlink:type="simple" />
  <link: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" />
  <link: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" />
  <link: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" />
  <link: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" />
  <link:definitionLink xlink:role="http://eme.edison.com/role/StatementOfTotalEquity" xlink:type="extended">
    <link:loc xlink:href="http://taxonomies.xbrl.us/us-gaap/2009/elts/us-gaap-2009-01-31.xsd#us-gaap_StatementLineItems" xlink:label="StatementLineItems" xlink:title="StatementLineItems" xlink:type="locator" />
    <link:loc xlink:href="http://taxonomies.xbrl.us/us-gaap/2009/elts/us-gaap-2009-01-31.xsd#us-gaap_StatementTable" xlink:label="StatementTable" xlink:title="StatementTable" xlink:type="locator" />
    <link:definitionArc order="1.0" p0:closed="true" p0:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="StatementLineItems" xlink:title="definition: StatementLineItems to StatementTable" xlink:to="StatementTable" xlink:type="arc" />
    <link:loc xlink:href="http://taxonomies.xbrl.us/us-gaap/2009/elts/us-gaap-2009-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="StatementEquityComponentsAxis" xlink:title="StatementEquityComponentsAxis" xlink:type="locator" />
    <link:definitionArc order="1.0" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="StatementTable" xlink:title="definition: StatementTable to StatementEquityComponentsAxis" xlink:to="StatementEquityComponentsAxis" xlink:type="arc" />
    <link:loc xlink:href="http://taxonomies.xbrl.us/us-gaap/2009/elts/us-gaap-2009-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="EquityComponentDomain" xlink:title="EquityComponentDomain" xlink:type="locator" />
    <link:definitionArc order="1.0" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="StatementEquityComponentsAxis" xlink:title="definition: StatementEquityComponentsAxis to EquityComponentDomain" xlink:to="EquityComponentDomain" xlink:type="arc" />
    <link:loc xlink:href="http://taxonomies.xbrl.us/us-gaap/2009/elts/us-gaap-2009-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="EquityComponentDomain_2" xlink:title="EquityComponentDomain" xlink:type="locator" />
    <link:definitionArc order="2.0" priority="1" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="StatementEquityComponentsAxis" xlink:title="definition: StatementEquityComponentsAxis to EquityComponentDomain" xlink:to="EquityComponentDomain_2" xlink:type="arc" />
    <link:loc xlink:href="http://taxonomies.xbrl.us/us-gaap/2009/elts/us-gaap-2009-01-31.xsd#us-gaap_ParentMember" xlink:label="ParentMember" xlink:title="ParentMember" xlink:type="locator" />
    <link:definitionArc order="1.0" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="EquityComponentDomain" xlink:title="definition: EquityComponentDomain to ParentMember" xlink:to="ParentMember" xlink:type="arc" />
    <link:loc xlink:href="http://taxonomies.xbrl.us/us-gaap/2009/elts/us-gaap-2009-01-31.xsd#us-gaap_CommonStockMember" xlink:label="CommonStockMember" xlink:title="CommonStockMember" xlink:type="locator" />
    <link:definitionArc order="1.0" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ParentMember" xlink:title="definition: ParentMember to CommonStockMember" xlink:to="CommonStockMember" xlink:type="arc" />
    <link:loc xlink:href="http://taxonomies.xbrl.us/us-gaap/2009/elts/us-gaap-2009-01-31.xsd#us-gaap_AdditionalPaidInCapitalMember" xlink:label="AdditionalPaidInCapitalMember" xlink:title="AdditionalPaidInCapitalMember" xlink:type="locator" />
    <link:definitionArc order="2.0" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ParentMember" xlink:title="definition: ParentMember to AdditionalPaidInCapitalMember" xlink:to="AdditionalPaidInCapitalMember" xlink:type="arc" />
    <link:loc xlink:href="http://taxonomies.xbrl.us/us-gaap/2009/elts/us-gaap-2009-01-31.xsd#us-gaap_RetainedEarningsMember" xlink:label="RetainedEarningsMember" xlink:title="RetainedEarningsMember" xlink:type="locator" />
    <link:definitionArc order="3.0" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ParentMember" xlink:title="definition: ParentMember to RetainedEarningsMember" xlink:to="RetainedEarningsMember" xlink:type="arc" />
    <link:loc xlink:href="http://taxonomies.xbrl.us/us-gaap/2009/elts/us-gaap-2009-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember" xlink:label="AccumulatedOtherComprehensiveIncomeMember" xlink:title="AccumulatedOtherComprehensiveIncomeMember" xlink:type="locator" />
    <link:definitionArc order="4.0" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ParentMember" xlink:title="definition: ParentMember to AccumulatedOtherComprehensiveIncomeMember" xlink:to="AccumulatedOtherComprehensiveIncomeMember" xlink:type="arc" />
    <link:loc xlink:href="http://taxonomies.xbrl.us/us-gaap/2009/elts/us-gaap-2009-01-31.xsd#us-gaap_NoncontrollingInterestMember" xlink:label="NoncontrollingInterestMember" xlink:title="NoncontrollingInterestMember" xlink:type="locator" />
    <link:definitionArc order="2.0" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="EquityComponentDomain" xlink:title="definition: EquityComponentDomain to NoncontrollingInterestMember" xlink:to="NoncontrollingInterestMember" xlink:type="arc" />
    <link:loc xlink:href="http://taxonomies.xbrl.us/us-gaap/2009/elts/us-gaap-2009-01-31.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward" xlink:label="IncreaseDecreaseInStockholdersEquityRollForward" xlink:title="IncreaseDecreaseInStockholdersEquityRollForward" xlink:type="locator" />
    <link:definitionArc order="2.0" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="StatementLineItems" xlink:title="definition: StatementLineItems to IncreaseDecreaseInStockholdersEquityRollForward" xlink:to="IncreaseDecreaseInStockholdersEquityRollForward" xlink:type="arc" />
    <link:loc xlink:href="http://taxonomies.xbrl.us/us-gaap/2009/elts/us-gaap-2009-01-31.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" xlink:label="StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" xlink:title="StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" xlink:type="locator" />
    <link:definitionArc order="1.0" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="IncreaseDecreaseInStockholdersEquityRollForward" xlink:title="definition: IncreaseDecreaseInStockholdersEquityRollForward to StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" xlink:to="StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" xlink:type="arc" />
    <link:loc xlink:href="http://taxonomies.xbrl.us/us-gaap/2009/elts/us-gaap-2009-01-31.xsd#us-gaap_ProfitLoss" xlink:label="ProfitLoss" xlink:title="ProfitLoss" xlink:type="locator" />
    <link:definitionArc order="2.0" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="IncreaseDecreaseInStockholdersEquityRollForward" xlink:title="definition: IncreaseDecreaseInStockholdersEquityRollForward to ProfitLoss" xlink:to="ProfitLoss" xlink:type="arc" />
    <link:loc xlink:href="http://taxonomies.xbrl.us/us-gaap/2009/elts/us-gaap-2009-01-31.xsd#us-gaap_CumulativeEffectOfInitialAdoptionOfFIN48" xlink:label="CumulativeEffectOfInitialAdoptionOfFIN48" xlink:title="CumulativeEffectOfInitialAdoptionOfFIN48" xlink:type="locator" />
    <link:definitionArc order="3.0" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="IncreaseDecreaseInStockholdersEquityRollForward" xlink:title="definition: IncreaseDecreaseInStockholdersEquityRollForward to CumulativeEffectOfInitialAdoptionOfFIN48" xlink:to="CumulativeEffectOfInitialAdoptionOfFIN48" xlink:type="arc" />
    <link:loc xlink:href="http://taxonomies.xbrl.us/us-gaap/2009/elts/us-gaap-2009-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecrease" xlink:label="OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecrease" xlink:title="OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecrease" xlink:type="locator" />
    <link:definitionArc order="4.0" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="IncreaseDecreaseInStockholdersEquityRollForward" xlink:title="definition: IncreaseDecreaseInStockholdersEquityRollForward to OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecrease" xlink:to="OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecrease" xlink:type="arc" />
    <link:loc xlink:href="http://taxonomies.xbrl.us/us-gaap/2009/elts/us-gaap-2009-01-31.xsd#us-gaap_DividendsCommonStockCash" xlink:label="DividendsCommonStockCash" xlink:title="DividendsCommonStockCash" xlink:type="locator" />
    <link:definitionArc order="6.0" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="IncreaseDecreaseInStockholdersEquityRollForward" xlink:title="definition: IncreaseDecreaseInStockholdersEquityRollForward to DividendsCommonStockCash" xlink:to="DividendsCommonStockCash" xlink:type="arc" />
    <link:loc xlink:href="eme-20091231.xsd#eme_PaymentsToParentForStockPurchasesRelatedToStockBasedCompensation" xlink:label="PaymentsToEdisonInternationalForStockPurchasesRelatedToStockBasedCompensation" xlink:title="PaymentsToEdisonInternationalForStockPurchasesRelatedToStockBasedCompensation" xlink:type="locator" />
    <link:definitionArc order="7.0" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="IncreaseDecreaseInStockholdersEquityRollForward" xlink:title="definition: IncreaseDecreaseInStockholdersEquityRollForward to PaymentsToEdisonInternationalForStockPurchasesRelatedToStockBasedCompensation" xlink:to="PaymentsToEdisonInternationalForStockPurchasesRelatedToStockBasedCompensation" xlink:type="arc" />
    <link:loc xlink:href="http://taxonomies.xbrl.us/us-gaap/2009/elts/us-gaap-2009-01-31.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalTaxEffectFromShareBasedCompensation" xlink:label="AdjustmentsToAdditionalPaidInCapitalTaxEffectFromShareBasedCompensation" xlink:title="AdjustmentsToAdditionalPaidInCapitalTaxEffectFromShareBasedCompensation" xlink:type="locator" />
    <link:definitionArc order="8.0" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="IncreaseDecreaseInStockholdersEquityRollForward" xlink:title="definition: IncreaseDecreaseInStockholdersEquityRollForward to AdjustmentsToAdditionalPaidInCapitalTaxEffectFromShareBasedCompensation" xlink:to="AdjustmentsToAdditionalPaidInCapitalTaxEffectFromShareBasedCompensation" xlink:type="arc" />
    <link:loc xlink:href="http://taxonomies.xbrl.us/us-gaap/2009/elts/us-gaap-2009-01-31.xsd#us-gaap_MinorityInterestIncreaseFromStockIssuance" xlink:label="MinorityInterestIncreaseFromStockIssuance" xlink:title="MinorityInterestIncreaseFromStockIssuance" xlink:type="locator" />
    <link:definitionArc order="10.0" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="IncreaseDecreaseInStockholdersEquityRollForward" xlink:title="definition: IncreaseDecreaseInStockholdersEquityRollForward to MinorityInterestIncreaseFromStockIssuance" xlink:to="MinorityInterestIncreaseFromStockIssuance" xlink:type="arc" />
    <link:loc xlink:href="http://taxonomies.xbrl.us/us-gaap/2009/elts/us-gaap-2009-01-31.xsd#us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders" xlink:label="MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders" xlink:title="MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders" xlink:type="locator" />
    <link:definitionArc order="12.0" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="IncreaseDecreaseInStockholdersEquityRollForward" xlink:title="definition: IncreaseDecreaseInStockholdersEquityRollForward to MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders" xlink:to="MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders" xlink:type="arc" />
    <link:loc xlink:href="http://taxonomies.xbrl.us/us-gaap/2009/elts/us-gaap-2009-01-31.xsd#us-gaap_ProceedsFromContributionsFromParent" xlink:label="ProceedsFromContributionsFromParent" xlink:title="ProceedsFromContributionsFromParent" xlink:type="locator" />
    <link:definitionArc order="5.0" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="IncreaseDecreaseInStockholdersEquityRollForward" xlink:title="definition: IncreaseDecreaseInStockholdersEquityRollForward to ProceedsFromContributionsFromParent" xlink:to="ProceedsFromContributionsFromParent" xlink:type="arc" />
    <link:loc xlink:href="http://taxonomies.xbrl.us/us-gaap/2009/elts/us-gaap-2009-01-31.xsd#us-gaap_StockholdersEquityOther" xlink:label="StockholdersEquityOther" xlink:title="StockholdersEquityOther" xlink:type="locator" />
    <link:definitionArc order="9.0" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="IncreaseDecreaseInStockholdersEquityRollForward" xlink:title="definition: IncreaseDecreaseInStockholdersEquityRollForward to StockholdersEquityOther" xlink:to="StockholdersEquityOther" xlink:type="arc" />
    <link:loc xlink:href="eme-20091231.xsd#eme_CashContributionsFromNoncontrollingInterests" xlink:label="CashContributionsFromNoncontrollingInterests" xlink:title="CashContributionsFromNoncontrollingInterests" xlink:type="locator" />
    <link:definitionArc order="11.0" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="IncreaseDecreaseInStockholdersEquityRollForward" xlink:title="definition: IncreaseDecreaseInStockholdersEquityRollForward to CashContributionsFromNoncontrollingInterests" xlink:to="CashContributionsFromNoncontrollingInterests" xlink:type="arc" />
    <link:loc xlink:href="http://taxonomies.xbrl.us/us-gaap/2009/elts/us-gaap-2009-01-31.xsd#us-gaap_StockholdersEquityPeriodIncreaseDecrease" xlink:label="StockholdersEquityPeriodIncreaseDecrease" xlink:title="StockholdersEquityPeriodIncreaseDecrease" xlink:type="locator" />
    <link:definitionArc order="100.0" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="IncreaseDecreaseInStockholdersEquityRollForward" xlink:title="definition: IncreaseDecreaseInStockholdersEquityRollForward to StockholdersEquityPeriodIncreaseDecrease" xlink:to="StockholdersEquityPeriodIncreaseDecrease" xlink:type="arc" />
  </link:definitionLink>
</link:linkbase>
