<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2015-08-11</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001411574</issuerCik>
        <issuerName>Surgical Care Affiliates, Inc.</issuerName>
        <issuerTradingSymbol>SCAI</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001495741</rptOwnerCik>
            <rptOwnerName>TPG Group Holdings (SBS) Advisors, Inc.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O TPG GLOBAL, LLC</rptOwnerStreet1>
            <rptOwnerStreet2>301 COMMERCE STREET, SUITE 3300</rptOwnerStreet2>
            <rptOwnerCity>FORT WORTH</rptOwnerCity>
            <rptOwnerState>TX</rptOwnerState>
            <rptOwnerZipCode>76102</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0000860866</rptOwnerCik>
            <rptOwnerName>BONDERMAN DAVID</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O TPG GLOBAL, LLC</rptOwnerStreet1>
            <rptOwnerStreet2>301 COMMERCE STREET, SUITE 3300</rptOwnerStreet2>
            <rptOwnerCity>FORT WORTH</rptOwnerCity>
            <rptOwnerState>TX</rptOwnerState>
            <rptOwnerZipCode>76102</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001099776</rptOwnerCik>
            <rptOwnerName>COULTER JAMES G</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O TPG GLOBAL, LLC</rptOwnerStreet1>
            <rptOwnerStreet2>301 COMMERCE STREET, SUITE 3300</rptOwnerStreet2>
            <rptOwnerCity>FORT WORTH</rptOwnerCity>
            <rptOwnerState>TX</rptOwnerState>
            <rptOwnerZipCode>76102</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2015-08-11</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>4000000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>37.68</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>12156480</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See Explanation of Responses</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">David Bonderman and James G. Coulter are officers and sole shareholders of TPG Group Holdings (SBS) Advisors, Inc. (&quot;Group Advisors&quot; and, together with Messrs. Bonderman and Coulter, the &quot;Reporting Persons&quot;), which is the general partner of TPG Group Holdings (SBS), L.P., which is the sole member of TPG Holdings I-A, LLC, which is the general partner of TPG Holdings I, L.P., which is the sole member of TPG GenPar V Advisors, LLC, which is the general partner of TPG GenPar V, L.P., which is the general partner of each of (i) TPG Partners V, L.P. (&quot;TPG Partners V&quot;), which directly holds 12,099,306 shares of Common Stock (each, a &quot;Share&quot;) of Surgical Care Affiliates, Inc. (the &quot;Issuer&quot;), (ii) TPG FOF V-A, L.P. (&quot;FOF V-A&quot;), which directly holds 31,652 Shares, and (iii) TPG FOF V-B, L.P. (&quot;FOF V-B&quot; and, together with TPG Partners V and FOF V-A, the &quot;TPG Funds&quot;), which directly holds 25,522 Shares.</footnote>
        <footnote id="F2">Because of the relationship between the Reporting Persons and the TPG Funds, the Reporting Persons may be deemed to beneficially own the securities reported herein to the extent of the greater of their respective direct or indirect pecuniary interests in the profits or capital accounts of the TPG Funds. Each Reporting Person and each of the TPG Funds disclaims beneficial ownership of the securities reported herein, except to the extent of such Reporting Person's or such TPG Fund's pecuniary interest therein, if any.</footnote>
        <footnote id="F3">Pursuant to Rule 16a-1(a)(4) under the Securities Exchange Act of 1934, as amended (the &quot;Exchange Act&quot;), this filing shall not be deemed an admission that the Reporting Persons are, for purposes of Section 16 of the Exchange Act or otherwise, the beneficial owners of any equity securities in excess of their respective pecuniary interests.</footnote>
    </footnotes>

    <remarks>(4) The Reporting Persons are jointly filing this Form 4 pursuant to Rule 16a-3(j) under the Exchange Act.

(5) Clive Bode is signing on behalf of both Messrs. Bonderman and Coulter pursuant to authorization and designation letters dated June 19, 2015, which were previously filed with the Securities and Exchange Commission.</remarks>

    <ownerSignature>
        <signatureName>/s/ Clive Bode, Vice President, TPG Group Holdings (SBS) Advisors, Inc. (4)</signatureName>
        <signatureDate>2015-08-12</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Clive Bode, on behalf of David Bonderman (4) (5)</signatureName>
        <signatureDate>2015-08-12</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Clive Bode, on behalf of James G. Coulter (4) (5)</signatureName>
        <signatureDate>2015-08-12</signatureDate>
    </ownerSignature>
</ownershipDocument>
