<?xml version="1.0" encoding="UTF-8"?><edgarSubmission xmlns="http://www.sec.gov/edgar/ownership" xmlns:ns2="http://www.sec.gov/edgar/common">
    <headerData>
        <submissionType>144</submissionType>
        <filerInfo>
            <filer>
                <filerCredentials>
                    <cik>0001816160</cik>
                    <ccc>XXXXXXXX</ccc>
                </filerCredentials>
            </filer>
            <liveTestFlag>LIVE</liveTestFlag>



        </filerInfo>
    </headerData>
    <formData>
        <issuerInfo>
            <issuerCik>0001070494</issuerCik>
            <issuerName>ACADIA PHARMACEUTICALS INC.</issuerName>
            <secFileNumber>000-50768</secFileNumber>
            <issuerAddress>
                <ns2:street1>12830 El Camino Real, Suite 400</ns2:street1>
                <ns2:city>San Diego</ns2:city>
                <ns2:stateOrCountry>CA</ns2:stateOrCountry>
                <ns2:zipCode>92130</ns2:zipCode>
            </issuerAddress>
            <issuerContactPhone>(858) 558-2871</issuerContactPhone>
            <nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>JAMES K KIHARA</nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>
            <relationshipsToIssuer>
                <relationshipToIssuer>Officer</relationshipToIssuer>
            </relationshipsToIssuer>
        </issuerInfo>
        <securitiesInformation>
            <securitiesClassTitle>Common</securitiesClassTitle>
            <brokerOrMarketmakerDetails>
                <name>Morgan Stanley Smith Barney LLC Executive Financial Services</name>
                <address>
                    <ns2:street1>1 New York Plaza</ns2:street1>
                    <ns2:street2>8th Floor</ns2:street2>
                    <ns2:city>New York</ns2:city>
                    <ns2:stateOrCountry>NY</ns2:stateOrCountry>
                    <ns2:zipCode>10004</ns2:zipCode>
                </address>
            </brokerOrMarketmakerDetails>
            <noOfUnitsSold>5401</noOfUnitsSold>
            <aggregateMarketValue>114394.11</aggregateMarketValue>
            <noOfUnitsOutstanding>171235870</noOfUnitsOutstanding>
            <approxSaleDate>05/26/2026</approxSaleDate>
            <securitiesExchangeName>NASDAQ</securitiesExchangeName>
        </securitiesInformation>
        <securitiesToBeSold>
            <securitiesClassTitle>Common</securitiesClassTitle>
            <acquiredDate>11/18/2024</acquiredDate>
            <natureOfAcquisitionTransaction>Performance Shares</natureOfAcquisitionTransaction>
            <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
            <isGiftTransaction>N</isGiftTransaction>
            <amountOfSecuritiesAcquired>3857</amountOfSecuritiesAcquired>
            <paymentDate>11/18/2024</paymentDate>
            <natureOfPayment>Not Applicable</natureOfPayment>
        </securitiesToBeSold>
        <securitiesToBeSold>
            <securitiesClassTitle>Common</securitiesClassTitle>
            <acquiredDate>11/13/2020</acquiredDate>
            <natureOfAcquisitionTransaction>Employee Stock Purchase Plan</natureOfAcquisitionTransaction>
            <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
            <isGiftTransaction>N</isGiftTransaction>
            <amountOfSecuritiesAcquired>491</amountOfSecuritiesAcquired>
            <paymentDate>11/13/2020</paymentDate>
            <natureOfPayment>Cash</natureOfPayment>
        </securitiesToBeSold>
        <securitiesToBeSold>
            <securitiesClassTitle>Common</securitiesClassTitle>
            <acquiredDate>05/13/2022</acquiredDate>
            <natureOfAcquisitionTransaction>Employee Stock Purchase Plan</natureOfAcquisitionTransaction>
            <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
            <isGiftTransaction>N</isGiftTransaction>
            <amountOfSecuritiesAcquired>1053</amountOfSecuritiesAcquired>
            <paymentDate>05/13/2022</paymentDate>
            <natureOfPayment>Cash</natureOfPayment>
        </securitiesToBeSold>
        <nothingToReportFlagOnSecuritiesSoldInPast3Months>N</nothingToReportFlagOnSecuritiesSoldInPast3Months>
        <securitiesSoldInPast3Months>
            <sellerDetails>
                <name>James Kihara</name>
                <address>
                    <ns2:street1>12830 El Camino Real, Suite 400</ns2:street1>
                    <ns2:city>San Diego</ns2:city>
                    <ns2:stateOrCountry>CA</ns2:stateOrCountry>
                    <ns2:zipCode>92130</ns2:zipCode>
                </address>
            </sellerDetails>
            <securitiesClassTitle>Common</securitiesClassTitle>
            <saleDate>05/04/2026</saleDate>
            <amountOfSecuritiesSold>1332</amountOfSecuritiesSold>
            <grossProceeds>29024.36</grossProceeds>
        </securitiesSoldInPast3Months>
        <securitiesSoldInPast3Months>
            <sellerDetails>
                <name>James Kihara</name>
                <address>
                    <ns2:street1>12830 El Camino Real, Suite 400</ns2:street1>
                    <ns2:city>San Diego</ns2:city>
                    <ns2:stateOrCountry>CA</ns2:stateOrCountry>
                    <ns2:zipCode>92130</ns2:zipCode>
                </address>
            </sellerDetails>
            <securitiesClassTitle>Common</securitiesClassTitle>
            <saleDate>04/07/2026</saleDate>
            <amountOfSecuritiesSold>1030</amountOfSecuritiesSold>
            <grossProceeds>22865.87</grossProceeds>
        </securitiesSoldInPast3Months>
        <securitiesSoldInPast3Months>
            <sellerDetails>
                <name>James Kihara</name>
                <address>
                    <ns2:street1>12830 El Camino Real, Suite 400</ns2:street1>
                    <ns2:city>San Diego</ns2:city>
                    <ns2:stateOrCountry>CA</ns2:stateOrCountry>
                    <ns2:zipCode>92130</ns2:zipCode>
                </address>
            </sellerDetails>
            <securitiesClassTitle>Common</securitiesClassTitle>
            <saleDate>03/26/2026</saleDate>
            <amountOfSecuritiesSold>1109</amountOfSecuritiesSold>
            <grossProceeds>24010.75</grossProceeds>
        </securitiesSoldInPast3Months>
        <securitiesSoldInPast3Months>
            <sellerDetails>
                <name>James Kihara</name>
                <address>
                    <ns2:street1>12830 El Camino Real, Suite 400</ns2:street1>
                    <ns2:city>San Diego</ns2:city>
                    <ns2:stateOrCountry>CA</ns2:stateOrCountry>
                    <ns2:zipCode>92130</ns2:zipCode>
                </address>
            </sellerDetails>
            <securitiesClassTitle>Common</securitiesClassTitle>
            <saleDate>03/25/2026</saleDate>
            <amountOfSecuritiesSold>833</amountOfSecuritiesSold>
            <grossProceeds>17884.51</grossProceeds>
        </securitiesSoldInPast3Months>
        <noticeSignature>
            <noticeDate>05/26/2026</noticeDate>
            <planAdoptionDates/>
            <signature>/s/ James Kihara</signature>
        </noticeSignature>
    </formData>
</edgarSubmission>
