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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2017-03-07</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001498511</rptOwnerCik>
            <rptOwnerName>Morton Andrew C.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>10910 DOMAIN DRIVE</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 300</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 - Human Resources</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2017-03-07</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>F</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>347</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>13.87</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>38033</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2017-03-08</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>F</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>822</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>13.77</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>37211</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2017-03-08</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>8000</value>
                    <footnoteId id="F2"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>45211</value>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Reflects payment of tax liability by withholding shares of stock incident to vesting of restricted stock previously issued.</footnote>
        <footnote id="F2">Represents a grant of time-based restricted stock under the Company's 2016 Omnibus Incentive Plan (the &quot;Plan&quot;), which vests to the extent of 25% annually beginning on March 8, 2018 and cumulatively vests to the extent of 25% each year thereafter.  The restricted stock being reported does not include the contingent right of the reporting person to receive up to 8,000 additional performance shares under the Plan based on the achievement of certain performance targets for the fiscal year 2017.</footnote>
        <footnote id="F3">Includes (i) unvested restricted shares which total 8,000 shares of stock from an initial grant of 8,000 shares of restricted stock that begins to vest on March 8, 2018;  (ii) unvested restricted shares which total 5,000 shares of stock from an initial grant of 5,000 shares of restricted stock that begins to vest on October 11, 2017; (iii) unvested restricted shares and fully vested shares totaling 7,347 shares of stock from an initial grant of 8,000 shares of restricted stock that begins to vest on March 7, 2017; (iv) unvested restricted shares and fully vested shares totaling 4,619 shares of stock from an initial grant of 4,958 shares of restricted stock made on November 10, 2015; (v) unvested restricted shares and fully vested shares totaling 3,546 shares of stock from an initial grant of 4,239 shares of restricted stock made on March 6, 2015; [continued in next footnote]</footnote>
        <footnote id="F4">(vi) unvested restricted shares and fully vested shares totaling 1,557 shares of stock from an initial grant of 2,064 shares of restricted stock made on March 7, 2014;(vii) unvested restricted shares and fully vested shares totaling 2,987 shares of stock from an initial grant of 3,958 shares of restricted stock and performance shares made on March 11, 2013; (viii) fully vested shares totaling 2,930 shares of stock from an initial grant of 5,000 shares of restricted stock made on March 7, 2012; (ix) fully vested shares totaling 3,060 shares of stock from an initial grant of 4,900 shares of restricted stock made on March 25, 2011; and (x) fully vested shares totaling 6,165 shares of stock from an initial grant of 12,000 shares of restricted stock made on June 21, 2010.  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 Andrew C. Morton</signatureName>
        <signatureDate>2017-03-09</signatureDate>
    </ownerSignature>
</ownershipDocument>
