<?xml version="1.0" encoding="us-ascii"?>
<!--XBRL document created by RR Donnelley IM Processor 5.0.0.0 using Fujitsu Interstage XWand-->
<schema targetNamespace="http://www.calvert.com/20121101" elementFormDefault="qualified" xmlns="http://www.w3.org/2001/XMLSchema" xmlns:cf4="http://www.calvert.com/20121101" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xbrli="http://www.xbrl.org/2003/instance" xmlns:nonnum="http://www.xbrl.org/dtr/type/non-numeric">
  <annotation>
    <appinfo>
      <link:linkbaseRef xlink:type="simple" xlink:href="cf4-20121101_pre.xml" xlink:title="Presentation Links, all" xlink:role="http://www.xbrl.org/2003/role/presentationLinkbaseRef" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" />
      <link:linkbaseRef xlink:type="simple" xlink:href="cf4-20121101_cal.xml" xlink:title="Calculation Links, all" xlink:role="http://www.xbrl.org/2003/role/calculationLinkbaseRef" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" />
      <link:linkbaseRef xlink:type="simple" xlink:href="cf4-20121101_def.xml" xlink:title="Definition Links, all" xlink:role="http://www.xbrl.org/2003/role/definitionLinkbaseRef" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" />
      <link:linkbaseRef xlink:type="simple" xlink:href="cf4-20121101_lab.xml" xlink:title="Label Links, all" xlink:role="http://www.xbrl.org/2003/role/labelLinkbaseRef" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" />
      <link:roleType roleURI="http://www.calvert.com/role/DocumentDocumentandEntityInformation" id="DocumentDocumentandEntityInformation">
        <link:definition>000000 - Document - Document and Entity Information</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.calvert.com/role/DocumentRiskReturnSummaryUnlabeledCalvertHighYieldBondFund" id="DocumentRiskReturnSummaryUnlabeledCalvertHighYieldBondFund">
        <link:definition>000011 - Document - Risk/Return Summary {Unlabeled} - Calvert High Yield Bond Fund</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.calvert.com/role/ScheduleShareholderFeesCalvertHighYieldBondFund" id="ScheduleShareholderFeesCalvertHighYieldBondFund">
        <link:definition>000012 - Schedule - Shareholder Fees {- Calvert High Yield Bond Fund}</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.calvert.com/role/ScheduleAnnualFundOperatingExpensesCalvertHighYieldBondFund" id="ScheduleAnnualFundOperatingExpensesCalvertHighYieldBondFund">
        <link:definition>000013 - Schedule - Annual Fund Operating Expenses {- Calvert High Yield Bond Fund}</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.calvert.com/role/ScheduleExpenseExampleTransposedCalvertHighYieldBondFund" id="ScheduleExpenseExampleTransposedCalvertHighYieldBondFund">
        <link:definition>000014 - Schedule - Expense Example {Transposed} {- Calvert High Yield Bond Fund}</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.calvert.com/role/ScheduleAnnualTotalReturnsCalvertHighYieldBondFundBarChart" id="ScheduleAnnualTotalReturnsCalvertHighYieldBondFundBarChart">
        <link:definition>000016 - Schedule - Annual Total Returns - Calvert High Yield Bond Fund [BarChart]</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.calvert.com/role/ScheduleAverageAnnualTotalReturnsTransposedCalvertHighYieldBondFund" id="ScheduleAverageAnnualTotalReturnsTransposedCalvertHighYieldBondFund">
        <link:definition>000017 - Schedule - Average Annual Total Returns {Transposed} {- Calvert High Yield Bond Fund}</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.calvert.com/role/DocumentRiskReturnDetailUnlabeledCalvertHighYieldBondFund" id="DocumentRiskReturnDetailUnlabeledCalvertHighYieldBondFund">
        <link:definition>000018 - Document - Risk/Return Detail {Unlabeled} - Calvert High Yield Bond Fund</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.calvert.com/role/DisclosureRiskReturnDetailDataElementsCalvertHighYieldBondFund" id="DisclosureRiskReturnDetailDataElementsCalvertHighYieldBondFund">
        <link:definition>000019 - Disclosure - Risk/Return Detail Data {Elements} - Calvert High Yield Bond Fund</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.calvert.com/role/DocumentRiskReturnSupplementUnlabeledCalvertHighYieldBondFund" id="DocumentRiskReturnSupplementUnlabeledCalvertHighYieldBondFund">
        <link:definition>000010 - Document - Risk/Return Supplement {Unlabeled} - Calvert High Yield Bond Fund</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
    </appinfo>
  </annotation>
  <import namespace="http://www.xbrl.org/2003/instance" schemaLocation="http://www.xbrl.org/2003/xbrl-instance-2003-12-31.xsd" />
  <import namespace="http://www.xbrl.org/2003/linkbase" schemaLocation="http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd" />
  <import namespace="http://xbrl.sec.gov/dei/2012-01-31" schemaLocation="http://xbrl.sec.gov/dei/2012/dei-2012-01-31.xsd" />
  <import namespace="http://xbrl.sec.gov/rr/2012-01-31" schemaLocation="http://xbrl.sec.gov/rr/2012/rr-2012-01-31.xsd" />
  <import namespace="http://www.xbrl.org/dtr/type/non-numeric" schemaLocation="http://www.xbrl.org/dtr/type/nonNumeric-2009-12-16.xsd" />
  <element name="S000025875Member" id="cf4_S000025875Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" />
  <element name="C000077416Member" id="cf4_C000077416Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" />
  <element name="C000077417Member" id="cf4_C000077417Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" />
  <element name="C000077418Member" id="cf4_C000077418Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" />
  <element name="C000105419Member" id="cf4_C000105419Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" />
  <element name="RetailMember" id="cf4_RetailMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" />
  <element name="SupplementTextBlock" id="cf4_SupplementTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" />
</schema>
