<?xml version="1.0" encoding="UTF-8"?><edgarSubmission xmlns="http://www.sec.gov/edgar/nport" xmlns:com="http://www.sec.gov/edgar/common" xmlns:ncom="http://www.sec.gov/edgar/nportcommon" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.sec.gov/edgar/nport eis_NPORT_Filer.xsd">
	<headerData>
		<submissionType>NPORT-P</submissionType>
		<isConfidential>false</isConfidential>
		<filerInfo>

			<filer>
				<issuerCredentials>
					<cik>0000076721</cik>
					<ccc>XXXXXXXX</ccc>
				</issuerCredentials>
			</filer>

			<seriesClassInfo>
				<seriesId>S000011971</seriesId>
				<classId>C000032681</classId>
				<classId>C000043250</classId>
				<classId>C000043251</classId>
			</seriesClassInfo>


		</filerInfo>
	</headerData>
	<formData>
		<genInfo>
			<regName>Impax Funds Series Trust I</regName>
			<regFileNumber>811-02064</regFileNumber>
			<regCik>0000076721</regCik>
			<regLei>549300TD5R23SWU72456</regLei>
			<regStreet1>30 Penhallow St.</regStreet1>
			<regStreet2>Suite 400</regStreet2>
			<regCity>Portsmouth</regCity>
			<regStateConditional regCountry="US" regState="US-NH"/>
			<regZipOrPostalCode>03801</regZipOrPostalCode>
			<regPhone>800-767-1729</regPhone>
			<seriesName>Impax Sustainable Allocation Fund</seriesName>
			<seriesId>S000011971</seriesId>
			<seriesLei>5493005QNFIONEGYS209</seriesLei>
			<repPdEnd>2022-12-31</repPdEnd>
			<repPdDate>2022-12-31</repPdDate>
			<isFinalFiling>N</isFinalFiling>
		</genInfo>
		<fundInfo>
			<totAssets>2144093766.09</totAssets>
			<totLiabs>374768.11</totLiabs>
			<netAssets>2143718997.98</netAssets>
			<assetsAttrMiscSec>0</assetsAttrMiscSec>
			<assetsInvested>0</assetsInvested>
			<amtPayOneYrBanksBorr>0</amtPayOneYrBanksBorr>
			<amtPayOneYrCtrldComp>0</amtPayOneYrCtrldComp>
			<amtPayOneYrOthAffil>0</amtPayOneYrOthAffil>
			<amtPayOneYrOther>0</amtPayOneYrOther>
			<amtPayAftOneYrBanksBorr>0</amtPayAftOneYrBanksBorr>
			<amtPayAftOneYrCtrldComp>0</amtPayAftOneYrCtrldComp>
			<amtPayAftOneYrOthAffil>0</amtPayAftOneYrOthAffil>
			<amtPayAftOneYrOther>0</amtPayAftOneYrOther>
			<delayDeliv>0</delayDeliv>
			<standByCommit>0</standByCommit>
			<liquidPref>0</liquidPref>
			<cshNotRptdInCorD>0</cshNotRptdInCorD>
			<isNonCashCollateral>N</isNonCashCollateral>
			<returnInfo>
				<monthlyTotReturns>
					<monthlyTotReturn classId="C000043250" rtn1="-3.49" rtn2="5.25" rtn3="4.24"/>
					<monthlyTotReturn classId="C000043251" rtn1="-3.45" rtn2="5.27" rtn3="4.24"/>
				</monthlyTotReturns>
				<monthlyReturnCats/>
				<othMon1 netRealizedGain="22597024.18" netUnrealizedAppr="-109652411.45"/>
				<othMon2 netRealizedGain="0" netUnrealizedAppr="109499173.55"/>
				<othMon3 netRealizedGain="3010.71" netUnrealizedAppr="84060566.7"/>
			</returnInfo>
			<mon1Flow redemption="33939802.42" reinvestment="6164683.67" sales="38545283.85"/>
			<mon2Flow redemption="15843548.05" reinvestment="0" sales="8999513.51"/>
			<mon3Flow redemption="15587668.04" reinvestment="0" sales="8461011.18"/>
		</fundInfo>
		<invstOrSecs>
			<invstOrSec>
				<name>IMPAX CORE BOND FUND</name>
				<lei>N/A</lei>
				<title>IMPAX CORE BOND FUND INST</title>
				<cusip>704223460</cusip>
				<identifiers>
					<isin value="US7042234606"/>
					<ticker value="PXBIX"/>
				</identifiers>
				<balance>85316698.738</balance>
				<units>NS</units>
				<curCd>USD</curCd>
				<valUSD>740548945.05</valUSD>
				<pctVal>34.545056779728</pctVal>
				<payoffProfile>Long</payoffProfile>
				<assetCat>EC</assetCat>
				<issuerCat>RF</issuerCat>
				<invCountry>US</invCountry>

				<isRestrictedSec>N</isRestrictedSec>

				<fairValLevel>1</fairValLevel>
				<securityLending>
					<isCashCollateral>N</isCashCollateral>
					<isNonCashCollateral>N</isNonCashCollateral>
					<isLoanByFund>N</isLoanByFund>
				</securityLending>
			</invstOrSec>
			<invstOrSec>
				<name>IMPAX ELLEVATE GLOBAL WOMEN S</name>
				<lei>N/A</lei>
				<title>IMPAX ELLEVATE GL WMS LE INS</title>
				<cusip>70422T109</cusip>
				<identifiers>
					<isin value="US70422T1097"/>
					<ticker value="PXWIX"/>
				</identifiers>
				<balance>2057972.73</balance>
				<units>NS</units>
				<curCd>USD</curCd>
				<valUSD>56491351.44</valUSD>
				<pctVal>2.635203190961</pctVal>
				<payoffProfile>Long</payoffProfile>
				<assetCat>EC</assetCat>
				<issuerCat>RF</issuerCat>
				<invCountry>US</invCountry>

				<isRestrictedSec>N</isRestrictedSec>

				<fairValLevel>1</fairValLevel>
				<securityLending>
					<isCashCollateral>N</isCashCollateral>
					<isNonCashCollateral>N</isNonCashCollateral>
					<isLoanByFund>N</isLoanByFund>
				</securityLending>
			</invstOrSec>
			<invstOrSec>
				<name>IMPAX FUNDS SERIES TRUST I   I</name>
				<lei>N/A</lei>
				<title>IMPAX INTL SUST ECO FUND INS</title>
				<cusip>704223742</cusip>
				<identifiers>
					<isin value="US7042237427"/>
					<ticker value="PXNIX"/>
				</identifiers>
				<balance>11578383.947</balance>
				<units>NS</units>
				<curCd>USD</curCd>
				<valUSD>99689885.78</valUSD>
				<pctVal>4.650324313678</pctVal>
				<payoffProfile>Long</payoffProfile>
				<assetCat>EC</assetCat>
				<issuerCat>RF</issuerCat>
				<invCountry>US</invCountry>

				<isRestrictedSec>N</isRestrictedSec>

				<fairValLevel>1</fairValLevel>
				<securityLending>
					<isCashCollateral>N</isCashCollateral>
					<isNonCashCollateral>N</isNonCashCollateral>
					<isLoanByFund>N</isLoanByFund>
				</securityLending>
			</invstOrSec>
			<invstOrSec>
				<name>IMPAX FUNDS SERIES TRUST I   I</name>
				<lei>N/A</lei>
				<title>IMPAX GLB SUST INFRA FD INST</title>
				<cusip>704223445</cusip>
				<identifiers>
					<isin value="US7042234457"/>
					<ticker value="PXDIX"/>
				</identifiers>
				<balance>7971318.507</balance>
				<units>NS</units>
				<curCd>USD</curCd>
				<valUSD>68314199.6</valUSD>
				<pctVal>3.186714287851</pctVal>
				<payoffProfile>Long</payoffProfile>
				<assetCat>EC</assetCat>
				<issuerCat>RF</issuerCat>
				<invCountry>US</invCountry>

				<isRestrictedSec>N</isRestrictedSec>

				<fairValLevel>1</fairValLevel>
				<securityLending>
					<isCashCollateral>N</isCashCollateral>
					<isNonCashCollateral>N</isNonCashCollateral>
					<isLoanByFund>N</isLoanByFund>
				</securityLending>
			</invstOrSec>
			<invstOrSec>
				<name>IMPAX GLOBAL ENVIRONMENTAL MAR</name>
				<lei>N/A</lei>
				<title>IMPAX GLBL ENV MKT INS</title>
				<cusip>704223775</cusip>
				<identifiers>
					<isin value="US7042237757"/>
					<ticker value="PGINX"/>
				</identifiers>
				<balance>2635834.721</balance>
				<units>NS</units>
				<curCd>USD</curCd>
				<valUSD>51609643.84</valUSD>
				<pctVal>2.407481758973</pctVal>
				<payoffProfile>Long</payoffProfile>
				<assetCat>EC</assetCat>
				<issuerCat>RF</issuerCat>
				<invCountry>US</invCountry>

				<isRestrictedSec>N</isRestrictedSec>

				<fairValLevel>1</fairValLevel>
				<securityLending>
					<isCashCollateral>N</isCashCollateral>
					<isNonCashCollateral>N</isNonCashCollateral>
					<isLoanByFund>N</isLoanByFund>
				</securityLending>
			</invstOrSec>
			<invstOrSec>
				<name>IMPAX GLOBAL OPPORTUNITIES FUN</name>
				<lei>N/A</lei>
				<title>IMPAX GLOBAL OPPORT INST</title>
				<cusip>704223429</cusip>
				<identifiers>
					<isin value="US7042234291"/>
					<ticker value="PXGOX"/>
				</identifiers>
				<balance>4082111.057</balance>
				<units>NS</units>
				<curCd>USD</curCd>
				<valUSD>56129027.03</valUSD>
				<pctVal>2.618301516332</pctVal>
				<payoffProfile>Long</payoffProfile>
				<assetCat>EC</assetCat>
				<issuerCat>RF</issuerCat>
				<invCountry>US</invCountry>

				<isRestrictedSec>N</isRestrictedSec>

				<fairValLevel>1</fairValLevel>
				<securityLending>
					<isCashCollateral>N</isCashCollateral>
					<isNonCashCollateral>N</isNonCashCollateral>
					<isLoanByFund>N</isLoanByFund>
				</securityLending>
			</invstOrSec>
			<invstOrSec>
				<name>IMPAX HIGH YIELD BOND FUND</name>
				<lei>N/A</lei>
				<title>IMPAX HIGH YIELD BOND IN</title>
				<cusip>704223809</cusip>
				<identifiers>
					<isin value="US7042238094"/>
					<ticker value="PXHIX"/>
				</identifiers>
				<balance>16220309.593</balance>
				<units>NS</units>
				<curCd>USD</curCd>
				<valUSD>92617967.78</valUSD>
				<pctVal>4.320434155189</pctVal>
				<payoffProfile>Long</payoffProfile>
				<assetCat>EC</assetCat>
				<issuerCat>RF</issuerCat>
				<invCountry>US</invCountry>

				<isRestrictedSec>N</isRestrictedSec>

				<fairValLevel>1</fairValLevel>
				<securityLending>
					<isCashCollateral>N</isCashCollateral>
					<isNonCashCollateral>N</isNonCashCollateral>
					<isLoanByFund>N</isLoanByFund>
				</securityLending>
			</invstOrSec>
			<invstOrSec>
				<name>IMPAX LARGE CAP FUND</name>
				<lei>N/A</lei>
				<title>IMPAX LARGE CAP FUND INST</title>
				<cusip>704223486</cusip>
				<identifiers>
					<isin value="US7042234861"/>
					<ticker value="PXLIX"/>
				</identifiers>
				<balance>75268532.501</balance>
				<units>NS</units>
				<curCd>USD</curCd>
				<valUSD>870104235.71</valUSD>
				<pctVal>40.588539660743</pctVal>
				<payoffProfile>Long</payoffProfile>
				<assetCat>EC</assetCat>
				<issuerCat>RF</issuerCat>
				<invCountry>US</invCountry>

				<isRestrictedSec>N</isRestrictedSec>

				<fairValLevel>1</fairValLevel>
				<securityLending>
					<isCashCollateral>N</isCashCollateral>
					<isNonCashCollateral>N</isNonCashCollateral>
					<isLoanByFund>N</isLoanByFund>
				</securityLending>
			</invstOrSec>
			<invstOrSec>
				<name>IMPAX SMALL CAP FUND</name>
				<lei>N/A</lei>
				<title>IMPAX SMALL CAP INS</title>
				<cusip>704223817</cusip>
				<identifiers>
					<isin value="US7042238177"/>
					<ticker value="PXSIX"/>
				</identifiers>
				<balance>4176979.978</balance>
				<units>NS</units>
				<curCd>USD</curCd>
				<valUSD>59689043.89</valUSD>
				<pctVal>2.784368844342</pctVal>
				<payoffProfile>Long</payoffProfile>
				<assetCat>EC</assetCat>
				<issuerCat>RF</issuerCat>
				<invCountry>US</invCountry>

				<isRestrictedSec>N</isRestrictedSec>

				<fairValLevel>1</fairValLevel>
				<securityLending>
					<isCashCollateral>N</isCashCollateral>
					<isNonCashCollateral>N</isNonCashCollateral>
					<isLoanByFund>N</isLoanByFund>
				</securityLending>
			</invstOrSec>
			<invstOrSec>
				<name>SSC GOVERNMENT MM GVMXX</name>
				<lei>N/A</lei>
				<title>SSC GOVERNMENT MM GVMXX</title>
				<cusip>7839989D1</cusip>
				<identifiers>
					<other otherDesc="Additional identifier not available." value="N/A"/>
				</identifiers>
				<balance>47588603.5</balance>
				<units>NS</units>
				<curCd>USD</curCd>
				<valUSD>47588603.5</valUSD>
				<pctVal>2.2199086515</pctVal>
				<payoffProfile>Long</payoffProfile>
				<assetCat>STIV</assetCat>
				<issuerCat>CORP</issuerCat>
				<invCountry>US</invCountry>

				<isRestrictedSec>N</isRestrictedSec>

				<fairValLevel>1</fairValLevel>
				<securityLending>
					<isCashCollateral>N</isCashCollateral>
					<isNonCashCollateral>N</isNonCashCollateral>
					<isLoanByFund>N</isLoanByFund>
				</securityLending>
			</invstOrSec>
		</invstOrSecs>
		<signature>
			<ncom:dateSigned>2023-02-28</ncom:dateSigned>
			<ncom:nameOfApplicant>Impax Funds Series Trust I</ncom:nameOfApplicant>
			<ncom:signature>/s/ Alicia DuBois</ncom:signature>
			<ncom:signerName>Alicia DuBois</ncom:signerName>
			<ncom:title>Treasurer</ncom:title>
		</signature>
	</formData>
</edgarSubmission>
