<?xml version="1.0" encoding="UTF-8"?>
<edgarSubmission xmlns="http://www.sec.gov/edgar/thirteenffiler" xmlns:com="http://www.sec.gov/edgar/common">
  <headerData>
    <submissionType>13F-HR</submissionType>
    <filerInfo>
      <liveTestFlag>LIVE</liveTestFlag>
      <flags>
        <confirmingCopyFlag>false</confirmingCopyFlag>
        <returnCopyFlag>true</returnCopyFlag>
        <overrideInternetFlag>false</overrideInternetFlag>
      </flags>
      <filer>
        <credentials>
          <cik>0001109448</cik>
          <ccc>XXXXXXXX</ccc>
        </credentials>
      </filer>
      <periodOfReport>12-31-2018</periodOfReport>
    </filerInfo>
  </headerData>
  <formData>
    <coverPage>
      <reportCalendarOrQuarter>12-31-2018</reportCalendarOrQuarter>
      <filingManager>
        <name>ALLIANCEBERNSTEIN L.P.</name>
        <address>
          <com:street1>1345 AVENUE OF THE AMERICAS</com:street1>
          <com:city>NEW YORK</com:city>
          <com:stateOrCountry>NY</com:stateOrCountry>
          <com:zipCode>10105</com:zipCode>
        </address>
      </filingManager>
      <reportType>13F HOLDINGS REPORT</reportType>
      <form13FFileNumber>028-10562</form13FFileNumber>
      <provideInfoForInstruction5>Y</provideInfoForInstruction5>
      <additionalInformation>All media outlets, please contact Andrea Prochniak at AllianceBernstein (212-756-4542) with any questions. All other questions can be directed to Section13USFilings@alliancebernstein.com.</additionalInformation>
    </coverPage>
    <signatureBlock>
      <name>Laurence Bertan</name>
      <title>SVP and Head of Regulatory Reporting</title>
      <phone>212-969-1309</phone>
      <signature>Laurence Bertan</signature>
      <city>New York</city>
      <stateOrCountry>NY</stateOrCountry>
      <signatureDate>02-13-2019</signatureDate>
    </signatureBlock>
    <summaryPage>
      <otherIncludedManagersCount>5</otherIncludedManagersCount>
      <tableEntryTotal>3118</tableEntryTotal>
      <tableValueTotal>134679983</tableValueTotal>
      <isConfidentialOmitted>false</isConfidentialOmitted>
      <otherManagers2Info>
        <otherManager2>
          <sequenceNumber>1</sequenceNumber>
          <otherManager>
            <cik>0000941620</cik>
            <form13FFileNumber>028-10563</form13FFileNumber>
            <name>AXA ASSURANCES I A R D MUTUELLE ET AL</name>
          </otherManager>
        </otherManager2>
        <otherManager2>
          <sequenceNumber>2</sequenceNumber>
          <otherManager>
            <cik>0000898482</cik>
            <form13FFileNumber>028-03638</form13FFileNumber>
            <name>AXA ASSURANCES VIE MUTUELLE ET AL</name>
          </otherManager>
        </otherManager2>
        <otherManager2>
          <sequenceNumber>3</sequenceNumber>
          <otherManager>
            <cik>0000898427</cik>
            <form13FFileNumber>028-03570</form13FFileNumber>
            <name>AXA</name>
          </otherManager>
        </otherManager2>
        <otherManager2>
          <sequenceNumber>4</sequenceNumber>
          <otherManager>
            <cik>0000888002</cik>
            <form13FFileNumber>028-03344</form13FFileNumber>
            <name>AXA FINANCIAL INC</name>
          </otherManager>
        </otherManager2>
        <otherManager2>
          <sequenceNumber>5</sequenceNumber>
          <otherManager>
            <cik>0000750443</cik>
            <form13FFileNumber>028-01432</form13FFileNumber>
            <name>STEWART W P &amp; CO LTD</name>
          </otherManager>
        </otherManager2>
      </otherManagers2Info>
    </summaryPage>
  </formData>
</edgarSubmission>
