<SUBMISSION>
<ACCESSION-NUMBER>0001179110-18-008730
<TYPE>4
<PUBLIC-DOCUMENT-COUNT>1
<PERIOD>20180614
<FILING-DATE>20180618
<DATE-OF-FILING-DATE-CHANGE>20180618
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>Lewis Earl
<CIK>0001603551
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4
<ACT>34
<FILE-NUMBER>001-36376
<FILM-NUMBER>18905828
</FILING-VALUES>
<MAIL-ADDRESS>
<STREET1>C/O 2U, INC.
<STREET2>8201 CORPORATE DRIVE
<CITY>LANDOVER
<STATE>MD
<ZIP>20785
</MAIL-ADDRESS>
</REPORTING-OWNER>
<ISSUER>
<COMPANY-DATA>
<CONFORMED-NAME>2U, Inc.
<CIK>0001459417
<ASSIGNED-SIC>7372
<IRS-NUMBER>262335939
<STATE-OF-INCORPORATION>DE
<FISCAL-YEAR-END>1231
</COMPANY-DATA>
<BUSINESS-ADDRESS>
<STREET1>7900 HARKINS ROAD
<CITY>LANHAM
<STATE>MD
<ZIP>20706
<PHONE>(301) 892-4350
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>7900 HARKINS ROAD
<CITY>LANHAM
<STATE>MD
<ZIP>20706
</MAIL-ADDRESS>
<FORMER-COMPANY>
<FORMER-CONFORMED-NAME>2tor, Inc.
<DATE-CHANGED>20090324
</FORMER-COMPANY>
</ISSUER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>FORM 4 -
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2018-06-14</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001459417</issuerCik>
        <issuerName>2U, Inc.</issuerName>
        <issuerTradingSymbol>TWOU</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001603551</rptOwnerCik>
            <rptOwnerName>Lewis Earl</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O 2U, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>7900 HARKINS ROAD</rptOwnerStreet2>
            <rptOwnerCity>LANHAM</rptOwnerCity>
            <rptOwnerState>MD</rptOwnerState>
            <rptOwnerZipCode>20706</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2018-06-14</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>10393</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>95.74</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>7880</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">The price reported in Column 4 is a weighted average price.  These shares were sold in multiple transactions at prices ranging from $95.63 to $95.85, inclusive.  The reporting person undertakes to provide to 2U, Inc., any security holder of 2U, Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in footnote (1) to this Form 4.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Matthew Norden, attorney-in-fact</signatureName>
        <signatureDate>2018-06-18</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SUBMISSION>
