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

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2008-07-29</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001023734</issuerCik>
        <issuerName>BPZ RESOURCES, INC.</issuerName>
        <issuerTradingSymbol>BZP</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001328004</rptOwnerCik>
            <rptOwnerName>Briens Frederic</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>580 WESTLAKE PARK BLVD</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 525</rptOwnerStreet2>
            <rptOwnerCity>HOUSTON</rptOwnerCity>
            <rptOwnerState>TX</rptOwnerState>
            <rptOwnerZipCode>77079</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Chief Operating Officer</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2008-07-29</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>1300</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F5"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>18.619</value>
                    <footnoteId id="F3"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>802828</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2008-07-29</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>1200</value>
                    <footnoteId id="F2"/>
                    <footnoteId id="F5"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>19.764</value>
                    <footnoteId id="F4"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>801628</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Represents 13 independent sales of: 100 Shares at $18.24,100 Shares at $18.31,100 Shares at $18.36,100 Shares at $18.37,100 Shares at $18.455,100 Shares at $18.48,100 Shares at $18.52,100 Shares at $18.54,100 Shares at $18.62,100 Shares at $18.64,100 Shares at $19.10,100 Shares at $19.19 and 100 Shares at $19.22.</footnote>
        <footnote id="F2">Represents 8 independent sales of:  100 Shares at $19.44,100 Shares at $19.48,100 Shares at $19.48,100 Shares at $19.54,100 Shares at $19.57,100 Shares at $19.76,100 Shares at $19.90 and 500 Shares at $20.00.</footnote>
        <footnote id="F3">Execution price of each trade was between $18.24 and $19.22.</footnote>
        <footnote id="F4">Execution price of each trade was between $19.44 and $20.00.</footnote>
        <footnote id="F5">These shares were sold pursuant to the provisions of a Rule 10b(5)-1 Plan established in June 2008.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Frederic Briens</signatureName>
        <signatureDate>2008-07-29</signatureDate>
    </ownerSignature>
</ownershipDocument>
