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    <submissionType>13F-NT</submissionType>
    <filerInfo>
      <liveTestFlag>LIVE</liveTestFlag>
      <flags/>
      <filer>
        <credentials>
          <cik>0001749921</cik>
          <ccc>XXXXXXXX</ccc>
        </credentials>
      </filer>
      <periodOfReport>06-30-2024</periodOfReport>
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  <formData>
    <coverPage>
      <reportCalendarOrQuarter>06-30-2024</reportCalendarOrQuarter>
      <isAmendment>false</isAmendment>
      <filingManager>
        <name>EnerVest Investment Services, L.L.C.</name>
        <address>
          <ns1:street1>1001 Fannin Street</ns1:street1>
          <ns1:street2>Suite 800</ns1:street2>
          <ns1:city>Houston</ns1:city>
          <ns1:stateOrCountry>TX</ns1:stateOrCountry>
          <ns1:zipCode>77002</ns1:zipCode>
        </address>
      </filingManager>
      <reportType>13F NOTICE</reportType>
      <form13FFileNumber>028-19296</form13FFileNumber>
      <crdNumber>000297181</crdNumber>
      <secFileNumber>801-113436</secFileNumber>
      <otherManagersInfo>
        <otherManager>
          <form13FFileNumber>028-19289</form13FFileNumber>
          <crdNumber>000297222</crdNumber>
          <name>EnerVest, Ltd.</name>
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      </otherManagersInfo>
      <provideInfoForInstruction5>Y</provideInfoForInstruction5>
      <additionalInformation>EnerVest Investment Services, L.L.C. is the investment adviser for certain pooled investment vehicles controlled by EnerVest, Ltd.</additionalInformation>
    </coverPage>
    <signatureBlock>
      <name>Erika Anderson</name>
      <title>Chief Compliance Officer</title>
      <phone>(713) 659-3500</phone>
      <signature>/s/ Erika Anderson</signature>
      <city>Houston</city>
      <stateOrCountry>TX</stateOrCountry>
      <signatureDate>08-14-2024</signatureDate>
    </signatureBlock>
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