<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2024 Workiva-->
<!--r:1862a02b-ce35-4bd7-b17e-b2e51476d173,g:28cadfcc-c6c4-4ea1-9410-4f13d09fa739-->
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:seic="http://www.seic.com/20240930" xmlns:xbrli="http://www.xbrl.org/2003/instance" xmlns:dtr-types1="http://www.xbrl.org/dtr/type/2020-01-21" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xmlns:dtr-types="http://www.xbrl.org/dtr/type/2022-03-31" attributeFormDefault="unqualified" elementFormDefault="qualified" targetNamespace="http://www.seic.com/20240930">
  <xs:import namespace="http://fasb.org/srt/2024" schemaLocation="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd"/>
  <xs:import namespace="http://fasb.org/us-gaap/2024" schemaLocation="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd"/>
  <xs:import namespace="http://www.xbrl.org/2003/instance" schemaLocation="http://www.xbrl.org/2003/xbrl-instance-2003-12-31.xsd"/>
  <xs:import namespace="http://www.xbrl.org/2003/linkbase" schemaLocation="http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd"/>
  <xs:import namespace="http://www.xbrl.org/dtr/type/2020-01-21" schemaLocation="https://www.xbrl.org/dtr/type/2020-01-21/types.xsd"/>
  <xs:import namespace="http://www.xbrl.org/dtr/type/2022-03-31" schemaLocation="https://www.xbrl.org/dtr/type/2022-03-31/types.xsd"/>
  <xs:import namespace="http://xbrl.org/2005/xbrldt" schemaLocation="http://www.xbrl.org/2005/xbrldt-2005.xsd"/>
  <xs:import namespace="http://xbrl.sec.gov/country/2024" schemaLocation="https://xbrl.sec.gov/country/2024/country-2024.xsd"/>
  <xs:import namespace="http://xbrl.sec.gov/dei/2024" schemaLocation="https://xbrl.sec.gov/dei/2024/dei-2024.xsd"/>
  <xs:import namespace="http://xbrl.sec.gov/ecd/2024" schemaLocation="https://xbrl.sec.gov/ecd/2024/ecd-2024.xsd"/>
  <xs:annotation>
    <xs:appinfo>
      <link:linkbaseRef xmlns:xlink="http://www.w3.org/1999/xlink" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="seic-20240930_pre.xml" xlink:role="http://www.xbrl.org/2003/role/presentationLinkbaseRef" xlink:type="simple"/>
      <link:linkbaseRef xmlns:xlink="http://www.w3.org/1999/xlink" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="seic-20240930_def.xml" xlink:role="http://www.xbrl.org/2003/role/definitionLinkbaseRef" xlink:type="simple"/>
      <link:linkbaseRef xmlns:xlink="http://www.w3.org/1999/xlink" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="seic-20240930_lab.xml" xlink:role="http://www.xbrl.org/2003/role/labelLinkbaseRef" xlink:type="simple"/>
      <link:linkbaseRef xmlns:xlink="http://www.w3.org/1999/xlink" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="seic-20240930_cal.xml" xlink:role="http://www.xbrl.org/2003/role/calculationLinkbaseRef" xlink:type="simple"/>
      <link:roleType id="Coverpage" roleURI="http://www.seic.com/role/Coverpage">
        <link:definition>0000001 - Document - Cover page</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="ConsolidatedBalanceSheetsunaudited" roleURI="http://www.seic.com/role/ConsolidatedBalanceSheetsunaudited">
        <link:definition>9952151 - Statement - Consolidated Balance Sheets (unaudited)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="ConsolidatedBalanceSheetsunauditedParenthetical" roleURI="http://www.seic.com/role/ConsolidatedBalanceSheetsunauditedParenthetical">
        <link:definition>9952152 - Statement - Consolidated Balance Sheets (unaudited) (Parenthetical)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="ConsolidatedStatementsofOperationsunaudited" roleURI="http://www.seic.com/role/ConsolidatedStatementsofOperationsunaudited">
        <link:definition>9952153 - Statement - Consolidated Statements of Operations (unaudited)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="ConsolidatedStatementsofComprehensiveIncomeunaudited" roleURI="http://www.seic.com/role/ConsolidatedStatementsofComprehensiveIncomeunaudited">
        <link:definition>9952154 - Statement - Consolidated Statements of Comprehensive Income (unaudited)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="ConsolidatedStatementsofComprehensiveIncomeunauditedParenthetical" roleURI="http://www.seic.com/role/ConsolidatedStatementsofComprehensiveIncomeunauditedParenthetical">
        <link:definition>9952155 - Statement - Consolidated Statements of Comprehensive Income (unaudited) (Parenthetical)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="ConsolidatedStatementsofChangesinEquityunaudited" roleURI="http://www.seic.com/role/ConsolidatedStatementsofChangesinEquityunaudited">
        <link:definition>9952156 - Statement - Consolidated Statements of Changes in Equity (unaudited)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="ConsolidatedStatementsofChangesinEquityunauditedParenthetical" roleURI="http://www.seic.com/role/ConsolidatedStatementsofChangesinEquityunauditedParenthetical">
        <link:definition>9952157 - Statement - Consolidated Statements of Changes in Equity (unaudited) (Parenthetical)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="ConsolidatedCondensedStatementsofCashFlowsunaudited" roleURI="http://www.seic.com/role/ConsolidatedCondensedStatementsofCashFlowsunaudited">
        <link:definition>9952158 - Statement - Consolidated Condensed Statements of Cash Flows (unaudited)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SummaryofSignificantAccountingPolicies" roleURI="http://www.seic.com/role/SummaryofSignificantAccountingPolicies">
        <link:definition>9952159 - Disclosure - Summary of Significant Accounting Policies</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="InvestmentInUnconsolidatedAffiliate" roleURI="http://www.seic.com/role/InvestmentInUnconsolidatedAffiliate">
        <link:definition>9952160 - Disclosure - Investment In Unconsolidated Affiliate</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CompositionofCertainFinancialStatementCaptions" roleURI="http://www.seic.com/role/CompositionofCertainFinancialStatementCaptions">
        <link:definition>9952161 - Disclosure - Composition of Certain Financial Statement Captions</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="FairValueMeasurements" roleURI="http://www.seic.com/role/FairValueMeasurements">
        <link:definition>9952162 - Disclosure - Fair Value Measurements</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="MarketableSecurities" roleURI="http://www.seic.com/role/MarketableSecurities">
        <link:definition>9952163 - Disclosure - Marketable Securities</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="LineofCredit" roleURI="http://www.seic.com/role/LineofCredit">
        <link:definition>9952164 - Disclosure - Line of Credit</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="ShareholdersEquity" roleURI="http://www.seic.com/role/ShareholdersEquity">
        <link:definition>9952165 - Disclosure - Shareholders' Equity</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="AccumulatedOtherComprehensiveLoss" roleURI="http://www.seic.com/role/AccumulatedOtherComprehensiveLoss">
        <link:definition>9952166 - Disclosure - Accumulated Other Comprehensive Loss</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="BusinessSegmentInformation" roleURI="http://www.seic.com/role/BusinessSegmentInformation">
        <link:definition>9952167 - Disclosure - Business Segment Information</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="IncomeTaxes" roleURI="http://www.seic.com/role/IncomeTaxes">
        <link:definition>9952168 - Disclosure - Income Taxes</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CommitmentsandContingencies" roleURI="http://www.seic.com/role/CommitmentsandContingencies">
        <link:definition>9952169 - Disclosure - Commitments and Contingencies</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="GoodwillandIntangibleAssets" roleURI="http://www.seic.com/role/GoodwillandIntangibleAssets">
        <link:definition>9952170 - Disclosure - Goodwill and Intangible Assets</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="RevenuesfromContractswithCustomers" roleURI="http://www.seic.com/role/RevenuesfromContractswithCustomers">
        <link:definition>9952171 - Disclosure - Revenues from Contracts with Customers</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SaleofProperty" roleURI="http://www.seic.com/role/SaleofProperty">
        <link:definition>9952172 - Disclosure - Sale of Property</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SummaryofSignificantAccountingPoliciesPolicies" roleURI="http://www.seic.com/role/SummaryofSignificantAccountingPoliciesPolicies">
        <link:definition>9954471 - Disclosure - Summary of Significant Accounting Policies (Policies)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SummaryofSignificantAccountingPoliciesTables" roleURI="http://www.seic.com/role/SummaryofSignificantAccountingPoliciesTables">
        <link:definition>9954472 - Disclosure - Summary of Significant Accounting Policies (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="InvestmentInUnconsolidatedAffiliateTables" roleURI="http://www.seic.com/role/InvestmentInUnconsolidatedAffiliateTables">
        <link:definition>9954473 - Disclosure - Investment In Unconsolidated Affiliate (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CompositionofCertainFinancialStatementCaptionsTables" roleURI="http://www.seic.com/role/CompositionofCertainFinancialStatementCaptionsTables">
        <link:definition>9954474 - Disclosure - Composition of Certain Financial Statement Captions (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="FairValueMeasurementsTables" roleURI="http://www.seic.com/role/FairValueMeasurementsTables">
        <link:definition>9954475 - Disclosure - Fair Value Measurements (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="MarketableSecuritiesTables" roleURI="http://www.seic.com/role/MarketableSecuritiesTables">
        <link:definition>9954476 - Disclosure - Marketable Securities (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="ShareholdersEquityTables" roleURI="http://www.seic.com/role/ShareholdersEquityTables">
        <link:definition>9954477 - Disclosure - Shareholders' Equity (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="AccumulatedOtherComprehensiveLossTables" roleURI="http://www.seic.com/role/AccumulatedOtherComprehensiveLossTables">
        <link:definition>9954478 - Disclosure - Accumulated Other Comprehensive Loss (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="BusinessSegmentInformationTables" roleURI="http://www.seic.com/role/BusinessSegmentInformationTables">
        <link:definition>9954479 - Disclosure - Business Segment Information (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="IncomeTaxesTables" roleURI="http://www.seic.com/role/IncomeTaxesTables">
        <link:definition>9954480 - Disclosure - Income Taxes (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="GoodwillandIntangibleAssetsTables" roleURI="http://www.seic.com/role/GoodwillandIntangibleAssetsTables">
        <link:definition>9954481 - Disclosure - Goodwill and Intangible Assets (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="RevenuesfromContractswithCustomersTables" roleURI="http://www.seic.com/role/RevenuesfromContractswithCustomersTables">
        <link:definition>9954482 - Disclosure - Revenues from Contracts with Customers (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SummaryofSignificantAccountingPoliciesNarrativeDetails" roleURI="http://www.seic.com/role/SummaryofSignificantAccountingPoliciesNarrativeDetails">
        <link:definition>9954483 - Disclosure - Summary of Significant Accounting Policies - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SummaryofSignificantAccountingPoliciesEarningsPerShareDetails" roleURI="http://www.seic.com/role/SummaryofSignificantAccountingPoliciesEarningsPerShareDetails">
        <link:definition>9954484 - Disclosure - Summary of Significant Accounting Policies - Earnings Per Share (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SummaryofSignificantAccountingPoliciesNetCashProvidedbyOperatingActivitiesDetails" roleURI="http://www.seic.com/role/SummaryofSignificantAccountingPoliciesNetCashProvidedbyOperatingActivitiesDetails">
        <link:definition>9954485 - Disclosure - Summary of Significant Accounting Policies - Net Cash Provided by Operating Activities (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="InvestmentInUnconsolidatedAffiliateNarrativeDetails" roleURI="http://www.seic.com/role/InvestmentInUnconsolidatedAffiliateNarrativeDetails">
        <link:definition>9954486 - Disclosure - Investment In Unconsolidated Affiliate - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="InvestmentInUnconsolidatedAffiliateCondensedStatementsofOperationsofLSVDetails" roleURI="http://www.seic.com/role/InvestmentInUnconsolidatedAffiliateCondensedStatementsofOperationsofLSVDetails">
        <link:definition>9954487 - Disclosure - Investment In Unconsolidated Affiliate - Condensed Statements of Operations of LSV (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="InvestmentinUnconsolidatedAffiliateCondensedBalanceSheetsofLSVDetails" roleURI="http://www.seic.com/role/InvestmentinUnconsolidatedAffiliateCondensedBalanceSheetsofLSVDetails">
        <link:definition>9954488 - Disclosure - Investment in Unconsolidated Affiliate - Condensed Balance Sheets of LSV (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CompositionofCertainFinancialStatementCaptionsReceivablesDetails" roleURI="http://www.seic.com/role/CompositionofCertainFinancialStatementCaptionsReceivablesDetails">
        <link:definition>9954489 - Disclosure - Composition of Certain Financial Statement Captions - Receivables (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CompositionofCertainFinancialStatementCaptionsPropertyAndEquipmentDetails" roleURI="http://www.seic.com/role/CompositionofCertainFinancialStatementCaptionsPropertyAndEquipmentDetails">
        <link:definition>9954490 - Disclosure - Composition of Certain Financial Statement Captions - Property And Equipment (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CompositionofCertainFinancialStatementCaptionsNarrativeDetails" roleURI="http://www.seic.com/role/CompositionofCertainFinancialStatementCaptionsNarrativeDetails">
        <link:definition>9954491 - Disclosure - Composition of Certain Financial Statement Captions - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CompositionofCertainFinancialStatementCaptionsAccruedLiabilitiesDetails" roleURI="http://www.seic.com/role/CompositionofCertainFinancialStatementCaptionsAccruedLiabilitiesDetails">
        <link:definition>9954492 - Disclosure - Composition of Certain Financial Statement Captions - Accrued Liabilities (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="FairValueMeasurementsDetails" roleURI="http://www.seic.com/role/FairValueMeasurementsDetails">
        <link:definition>9954493 - Disclosure - Fair Value Measurements (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="MarketableSecuritiesNarrativeDetails" roleURI="http://www.seic.com/role/MarketableSecuritiesNarrativeDetails">
        <link:definition>9954494 - Disclosure - Marketable Securities - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="MarketableSecuritiesAvailableforSaleandEquitySecuritiesDetails" roleURI="http://www.seic.com/role/MarketableSecuritiesAvailableforSaleandEquitySecuritiesDetails">
        <link:definition>9954495 - Disclosure - Marketable Securities - Available for Sale and Equity Securities (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="MarketableSecuritiesAvailableforSaleandEquitySecuritiesDetails_1" roleURI="http://www.seic.com/role/MarketableSecuritiesAvailableforSaleandEquitySecuritiesDetails_1">
        <link:definition>9954495 - Disclosure - Marketable Securities - Available for Sale and Equity Securities (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="MarketableSecuritiesScheduleofAvailableforSaleDebtSecuritiesbyMaturityDetails" roleURI="http://www.seic.com/role/MarketableSecuritiesScheduleofAvailableforSaleDebtSecuritiesbyMaturityDetails">
        <link:definition>9954496 - Disclosure - Marketable Securities - Schedule of Available-for-Sale Debt Securities by Maturity (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="LineofCreditDetails" roleURI="http://www.seic.com/role/LineofCreditDetails">
        <link:definition>9954497 - Disclosure - Line of Credit (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="ShareholdersEquityStockBasedCompensationExpenseDetails" roleURI="http://www.seic.com/role/ShareholdersEquityStockBasedCompensationExpenseDetails">
        <link:definition>9954498 - Disclosure - Shareholders' Equity - Stock-Based Compensation Expense (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="ShareholdersEquityNarrativeDetails" roleURI="http://www.seic.com/role/ShareholdersEquityNarrativeDetails">
        <link:definition>9954499 - Disclosure - Shareholders' Equity - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="AccumulatedOtherComprehensiveLossDetails" roleURI="http://www.seic.com/role/AccumulatedOtherComprehensiveLossDetails">
        <link:definition>9954500 - Disclosure - Accumulated Other Comprehensive Loss (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="BusinessSegmentInformationNarrativeDetails" roleURI="http://www.seic.com/role/BusinessSegmentInformationNarrativeDetails">
        <link:definition>9954501 - Disclosure - Business Segment Information - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="BusinessSegmentInformationScheduleofFinancialInformationAboutBusinessSegmentsDetails" roleURI="http://www.seic.com/role/BusinessSegmentInformationScheduleofFinancialInformationAboutBusinessSegmentsDetails">
        <link:definition>9954502 - Disclosure - Business Segment Information - Schedule of Financial Information About Business Segments (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="BusinessSegmentInformationReconciliationofTotalOperatingProfitDetails" roleURI="http://www.seic.com/role/BusinessSegmentInformationReconciliationofTotalOperatingProfitDetails">
        <link:definition>9954503 - Disclosure - Business Segment Information - Reconciliation of Total Operating Profit (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="BusinessSegmentInformationScheduleOfAdditionalInformationPertainingToBusinessSegmentsDetails" roleURI="http://www.seic.com/role/BusinessSegmentInformationScheduleOfAdditionalInformationPertainingToBusinessSegmentsDetails">
        <link:definition>9954504 - Disclosure - Business Segment Information - Schedule Of Additional Information Pertaining To Business Segments (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="IncomeTaxesNarrativeDetails" roleURI="http://www.seic.com/role/IncomeTaxesNarrativeDetails">
        <link:definition>9954505 - Disclosure - Income Taxes - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="IncomeTaxesInterestAndPenaltiesDetails" roleURI="http://www.seic.com/role/IncomeTaxesInterestAndPenaltiesDetails">
        <link:definition>9954506 - Disclosure - Income Taxes - Interest And Penalties (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="IncomeTaxesEffectiveIncomeTaxRateReconciliationDetails" roleURI="http://www.seic.com/role/IncomeTaxesEffectiveIncomeTaxRateReconciliationDetails">
        <link:definition>9954507 - Disclosure - Income Taxes - Effective Income Tax Rate Reconciliation (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CommitmentsandContingenciesDetails" roleURI="http://www.seic.com/role/CommitmentsandContingenciesDetails">
        <link:definition>9954508 - Disclosure - Commitments and Contingencies (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="GoodwillandIntangibleAssetsScheduleofGoodwillDetails" roleURI="http://www.seic.com/role/GoodwillandIntangibleAssetsScheduleofGoodwillDetails">
        <link:definition>9954509 - Disclosure - Goodwill and Intangible Assets - Schedule of Goodwill (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="GoodwillandIntangibleAssetsNarrativeDetails" roleURI="http://www.seic.com/role/GoodwillandIntangibleAssetsNarrativeDetails">
        <link:definition>9954510 - Disclosure - Goodwill and Intangible Assets - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="RevenuesfromContractswithCustomersDetails" roleURI="http://www.seic.com/role/RevenuesfromContractswithCustomersDetails">
        <link:definition>9954511 - Disclosure - Revenues from Contracts with Customers (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SaleofPropertyDetails" roleURI="http://www.seic.com/role/SaleofPropertyDetails">
        <link:definition>9954512 - Disclosure - Sale of Property (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
    </xs:appinfo>
  </xs:annotation>
  <xs:element id="seic_AssetManagementAdministrationAndDistributionFeesMember" abstract="true" name="AssetManagementAdministrationAndDistributionFeesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="seic_InformationProcessingAndSoftwareServicingFeesMember" abstract="true" name="InformationProcessingAndSoftwareServicingFeesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="seic_SubadvisoryDistributionAndOtherAssetManagementCosts" abstract="false" name="SubadvisoryDistributionAndOtherAssetManagementCosts" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="seic_SoftwareRoyaltiesAndOtherInformationProcessingCosts" abstract="false" name="SoftwareRoyaltiesAndOtherInformationProcessingCosts" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="seic_CompensationBenefitsAndOtherPersonnel" abstract="false" name="CompensationBenefitsAndOtherPersonnel" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="seic_SummaryOfSignificantAccountingPoliciesTable" abstract="true" name="SummaryOfSignificantAccountingPoliciesTable" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrldt:hypercubeItem" type="xbrli:stringItemType"/>
  <xs:element id="seic_SeiSponsoredOpenEndedMoneyMarketMutualFundsMember" abstract="true" name="SeiSponsoredOpenEndedMoneyMarketMutualFundsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="seic_SeiInvestmentsEuropeLimitedMember" abstract="true" name="SeiInvestmentsEuropeLimitedMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="seic_SeiInvestmentsDistributionCoSidcoMember" abstract="true" name="SeiInvestmentsDistributionCoSidcoMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="seic_SeiWealthPlatformMember" abstract="true" name="SeiWealthPlatformMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="seic_InvestmentManagersMember" abstract="true" name="InvestmentManagersMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="seic_SummaryofSignificantAccountingPoliciesLineItems" abstract="true" name="SummaryofSignificantAccountingPoliciesLineItems" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="seic_CapitalizedSoftwareDevelopmentCostsInProgress" abstract="false" name="CapitalizedSoftwareDevelopmentCostsInProgress" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="seic_CapitalizedContractCostsNetOfAmortization" abstract="false" name="CapitalizedContractCostsNetOfAmortization" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="seic_LSVAssetManagementMember" abstract="true" name="LSVAssetManagementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="seic_ReceivablesGrossCurrent" abstract="false" name="ReceivablesGrossCurrent" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="seic_PurchasedSoftwareMember" abstract="true" name="PurchasedSoftwareMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="seic_CapitalizedContractCostAmountCapitalizedDuringPeriod" abstract="false" name="CapitalizedContractCostAmountCapitalizedDuringPeriod" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="seic_AccruedVoluntarySeparationProgramCurrent" abstract="false" name="AccruedVoluntarySeparationProgramCurrent" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="seic_AccruedSubAdvisoryDistributionAndOtherAssetManagementFeesCurrent" abstract="false" name="AccruedSubAdvisoryDistributionAndOtherAssetManagementFeesCurrent" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="seic_InvestmentFundsSponsoredByLSVMember" abstract="true" name="InvestmentFundsSponsoredByLSVMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="seic_AccumulatedOtherComprehensiveIncomeLossDebtSecuritiesAvailableForSaleSecuritiesAdjustmentTax" abstract="false" name="AccumulatedOtherComprehensiveIncomeLossDebtSecuritiesAvailableForSaleSecuritiesAdjustmentTax" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="seic_SEISponsoredMutualFundsMember" abstract="true" name="SEISponsoredMutualFundsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="seic_EquitiesAndOtherMutualFundsMember" abstract="true" name="EquitiesAndOtherMutualFundsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="seic_EquitySecuritiesFVNIAccumulatedGrossUnrealizedGainBeforeTax" abstract="false" name="EquitySecuritiesFVNIAccumulatedGrossUnrealizedGainBeforeTax" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="seic_EquitySecuritiesFVNIAccumulatedGrossUnrealizedLossBeforeTax" abstract="false" name="EquitySecuritiesFVNIAccumulatedGrossUnrealizedLossBeforeTax" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="seic_DebtSecuritiesAvailableForSaleAndEquitySecuritiesFVNICost" abstract="false" name="DebtSecuritiesAvailableForSaleAndEquitySecuritiesFVNICost" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="seic_DebtSecuritiesAvailableForSaleAndEquitySecuritiesFVNIAccumulatedGrossUnrealizedGainBeforeTax" abstract="false" name="DebtSecuritiesAvailableForSaleAndEquitySecuritiesFVNIAccumulatedGrossUnrealizedGainBeforeTax" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="seic_DebtSecuritiesAvailableForSaleAndEquitySecuritiesFVNIAccumulatedGrossUnrealizedLossBeforeTax" abstract="false" name="DebtSecuritiesAvailableForSaleAndEquitySecuritiesFVNIAccumulatedGrossUnrealizedLossBeforeTax" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="seic_DebtSecuritiesAvailableForSaleAndEquitySecuritiesFVNI" abstract="false" name="DebtSecuritiesAvailableForSaleAndEquitySecuritiesFVNI" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="seic_A2021CreditFacilityMember" abstract="true" name="A2021CreditFacilityMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="seic_DebtInstrumentInterestRatesAccrualNumberOfPrecedingFiscalQuarters" abstract="false" name="DebtInstrumentInterestRatesAccrualNumberOfPrecedingFiscalQuarters" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="seic_LineOfCreditFacilityConditionalIncreaseDecreaseNet" abstract="false" name="LineOfCreditFacilityConditionalIncreaseDecreaseNet" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="seic_LineOfCreditFacilityFrontingFeePercentage" abstract="false" name="LineOfCreditFacilityFrontingFeePercentage" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:percentItemType"/>
  <xs:element id="seic_TwoThousandFourteenPlanMember" abstract="true" name="TwoThousandFourteenPlanMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="seic_CommonStockBuybackMember" abstract="true" name="CommonStockBuybackMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="seic_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardWaitingPeriod" abstract="false" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardWaitingPeriod" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="seic_ShareRepurchaseProgramAuthorizedAmountIncreaseDecrease" abstract="false" name="ShareRepurchaseProgramAuthorizedAmountIncreaseDecrease" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="seic_PrivateBankMember" abstract="true" name="PrivateBankMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="seic_InvestmentAdvisorsMember" abstract="true" name="InvestmentAdvisorsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="seic_InstitutionalInvestorsMember" abstract="true" name="InstitutionalInvestorsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="seic_InvestmentsInNewBusinessesMember" abstract="true" name="InvestmentsInNewBusinessesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="seic_SettlementandLapseofStatuteMember" abstract="true" name="SettlementandLapseofStatuteMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="seic_GrossLiabilityForUnrecognizedTaxBenefitsExclusiveOfInterestAndPenalties" abstract="false" name="GrossLiabilityForUnrecognizedTaxBenefitsExclusiveOfInterestAndPenalties" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="seic_EffectiveIncomeTaxRateReconciliationTaxBenefitFromStockOptionExercisesPercent" abstract="false" name="EffectiveIncomeTaxRateReconciliationTaxBenefitFromStockOptionExercisesPercent" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:percentItemType"/>
  <xs:element id="seic_RubiconWealthManagementMember" abstract="true" name="RubiconWealthManagementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="seic_RubiconWealthManagementStarSitronVs.SEIPrivateTrustCompanyMember" abstract="true" name="RubiconWealthManagementStarSitronVs.SEIPrivateTrustCompanyMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="seic_RubiconWealthManagementCharlesMurrayVs.SEIPrivateTrustCompanyMember" abstract="true" name="RubiconWealthManagementCharlesMurrayVs.SEIPrivateTrustCompanyMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="seic_NumberOfClientsWithCustodialAccounts" abstract="false" name="NumberOfClientsWithCustodialAccounts" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="seic_NumberOfAdditionalCasesFiled" abstract="false" name="NumberOfAdditionalCasesFiled" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="seic_NumberOfSuitsFiled" abstract="false" name="NumberOfSuitsFiled" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="seic_NumberOfFormalComplaintsFiled" abstract="false" name="NumberOfFormalComplaintsFiled" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="seic_NumberOfFormalComplaintsNotYetFiled" abstract="false" name="NumberOfFormalComplaintsNotYetFiled" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="seic_FactDiscoveryPeriodThreshold" abstract="false" name="FactDiscoveryPeriodThreshold" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="seic_DispositiveMotionsPeriodThreshold" abstract="false" name="DispositiveMotionsPeriodThreshold" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="seic_LossContingencyEstimatedClientAssets" abstract="false" name="LossContingencyEstimatedClientAssets" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="seic_XPSPensionsNexusLimitedMember" abstract="true" name="XPSPensionsNexusLimitedMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="seic_BusinessCombinationContingentConsiderationLiabilityPeriodOfRecognition" abstract="false" name="BusinessCombinationContingentConsiderationLiabilityPeriodOfRecognition" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="seic_InvestmentManagementFeesFromInvestmentProductsMember" abstract="true" name="InvestmentManagementFeesFromInvestmentProductsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="seic_InvestmentManagementFeesFromInvestmentManagementAgreementsMember" abstract="true" name="InvestmentManagementFeesFromInvestmentManagementAgreementsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="seic_InvestmentOperationsFeesMember" abstract="true" name="InvestmentOperationsFeesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="seic_InvestmentProcessingFeesPaaSMember" abstract="true" name="InvestmentProcessingFeesPaaSMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="seic_InvestmentProcessingFeesSaaSMember" abstract="true" name="InvestmentProcessingFeesSaaSMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="seic_ProfessionalServicesFeesMember" abstract="true" name="ProfessionalServicesFeesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="seic_AccountFeesAndOtherMember" abstract="true" name="AccountFeesAndOtherMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="seic_ProfessionalServicesFeesOneTimeEarlyTerminationFeesMember" abstract="true" name="ProfessionalServicesFeesOneTimeEarlyTerminationFeesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
</xs:schema>
