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

    <schemaVersion>X0206</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2018-10-15</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0000722723</issuerCik>
        <issuerName>HANGER, INC.</issuerName>
        <issuerTradingSymbol>HNGR</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001756677</rptOwnerCik>
            <rptOwnerName>Dobson Mitchell D</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>10910 DOMAIN DRIVE, SUITE 300</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>AUSTIN</rptOwnerCity>
            <rptOwnerState>TX</rptOwnerState>
            <rptOwnerZipCode>78758</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>SVP, Chief Compliance Officer</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>19635</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Consists of (i) unvested restricted shares totaling 5,000 shares of stock from an initial grant of 5,000  shares of restricted stock that begins to vest on March 9, 2019; (ii) unvested restricted shares and fully vested shares totaling 4,555 shares of stock from an initial grant of 5,000 shares of restricted stock that begins to vest on March 8, 2018; (iii) unvested restricted shares and fully vested shares totaling 3,379 shares of stock from an initial grant of 4,150 shares of restricted stock that begins to vest on April 29, 2017; (iv) unvested restricted shares and fully vested shares totaling 1,515 shares of stock from an initial grant of 1,653 shares of restricted stock made on November 10, 2015; [continued in next footnote]</footnote>
        <footnote id="F2">(v) unvested restricted shares and fully vested shares totaling 142 shares of stock from an initial grant of 200 shares of restricted stock made on March 6, 2015; (vi) unvested restricted shares and fully vested shares totaling 2,585 shares of stock from an initial grant of 3,604 shares of restricted stock made on March 6, 2015; (vii) fully vested shares totaling 990 shares of stock from an initial grant of 1,598 shares of restricted stock made on March 7, 2014 (viii) fully vested shares totaling 827 shares of stock from an initial grant of 1,800 shares of restricted stock made on March 11, 2013; (ix) fully vested shares totaling 428 shares from an initial grant of 1,400 shares of restricted stock made on March 7, 2012 and (x) fully vested shares totaling 214 shares from an initial grant of 1,400 shares of restricted stock made on March 25, 2011.</footnote>
        <footnote id="F3">Except as otherwise noted, all remaining unvested restricted shares will continue to vest at a rate of 25% per year of the original grant amount on the anniversary date of the grant.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Jessica Lochmann Allen, Attorney-in-Fact for Mitchell D. Dobson</signatureName>
        <signatureDate>2018-10-23</signatureDate>
    </ownerSignature>
</ownershipDocument>
