diff --git a/endpoints/openrtb2/auction.go b/endpoints/openrtb2/auction.go
index 20acc2aedd3..3fd2132143e 100644
--- a/endpoints/openrtb2/auction.go
+++ b/endpoints/openrtb2/auction.go
@@ -290,6 +290,10 @@ func (deps *endpointDeps) validateRequest(req *openrtb.BidRequest) []error {
 		if err := validateBidAdjustmentFactors(bidExt.Prebid.BidAdjustmentFactors, aliases); err != nil {
 			return []error{err}
 		}
+
+		if err := validateSChains(bidExt); err != nil {
+			return []error{err}
+		}
 	}
 
 	if (req.Site == nil && req.App == nil) || (req.Site != nil && req.App != nil) {
@@ -362,6 +366,11 @@ func validateBidAdjustmentFactors(adjustmentFactors map[string]float64, aliases
 	return nil
 }
 
+func validateSChains(req *openrtb_ext.ExtRequest) error {
+	_, err := exchange.BidderToPrebidSChains(req)
+	return err
+}
+
 func (deps *endpointDeps) validateImp(imp *openrtb.Imp, aliases map[string]string, index int) []error {
 	if imp.ID == "" {
 		return []error{fmt.Errorf("request.imp[%d] missing required field: \"id\"", index)}
diff --git a/endpoints/openrtb2/auction_test.go b/endpoints/openrtb2/auction_test.go
index 97f0038a392..c697c206483 100644
--- a/endpoints/openrtb2/auction_test.go
+++ b/endpoints/openrtb2/auction_test.go
@@ -1039,6 +1039,53 @@ func TestCCPAInvalid(t *testing.T) {
 	assert.Empty(t, req.Regs.Ext, "Invalid Consent Removed From Request")
 }
 
+func TestSChainInvalid(t *testing.T) {
+	deps := &endpointDeps{
+		&nobidExchange{},
+		newParamsValidator(t),
+		&mockStoredReqFetcher{},
+		empty_fetcher.EmptyFetcher{},
+		empty_fetcher.EmptyFetcher{},
+		&config.Configuration{},
+		pbsmetrics.NewMetrics(metrics.NewRegistry(), openrtb_ext.BidderList(), config.DisabledMetrics{}),
+		analyticsConf.NewPBSAnalytics(&config.Analytics{}),
+		map[string]string{},
+		false,
+		[]byte{},
+		openrtb_ext.BidderMap,
+		nil,
+		nil,
+		hardcodedResponseIPValidator{response: true},
+	}
+
+	ui := uint64(1)
+	req := openrtb.BidRequest{
+		ID: "someID",
+		Imp: []openrtb.Imp{
+			{
+				ID: "imp-ID",
+				Banner: &openrtb.Banner{
+					W: &ui,
+					H: &ui,
+				},
+				Ext: json.RawMessage(`{"appnexus": {"placementId": 5667}}`),
+			},
+		},
+		Site: &openrtb.Site{
+			ID: "myID",
+		},
+		Regs: &openrtb.Regs{
+			Ext: json.RawMessage(`{"us_privacy":"abcd"}`),
+		},
+		Ext: json.RawMessage(`{"prebid":{"schains":[{"bidders":["appnexus"],"schain":{"complete":1,"nodes":[{"asi":"directseller1.com","sid":"00001","rid":"BidRequest1","hp":1}],"ver":"1.0"}}, {"bidders":["appnexus"],"schain":{"complete":1,"nodes":[{"asi":"directseller2.com","sid":"00002","rid":"BidRequest2","hp":1}],"ver":"1.0"}}]}}`),
+	}
+
+	errL := deps.validateRequest(&req)
+
+	expectedError := fmt.Errorf("request.ext.prebid.schains contains multiple schains for bidder appnexus; it must contain no more than one per bidder.")
+	assert.ElementsMatch(t, errL, []error{expectedError})
+}
+
 func TestSanitizeRequest(t *testing.T) {
 	testCases := []struct {
 		description  string
diff --git a/exchange/utils.go b/exchange/utils.go
index 96c00ec0e36..4de985eca40 100644
--- a/exchange/utils.go
+++ b/exchange/utils.go
@@ -28,6 +28,29 @@ type cleanMetrics struct {
 	gdprTcfVersion int
 }
 
+func BidderToPrebidSChains(req *openrtb_ext.ExtRequest) (map[string]*openrtb_ext.ExtRequestPrebidSChainSChain, error) {
+	bidderToSChains := make(map[string]*openrtb_ext.ExtRequestPrebidSChainSChain)
+
+	if len(req.Prebid.SChains) == 0 {
+		return bidderToSChains, nil
+	}
+
+	for _, schainWrapper := range req.Prebid.SChains {
+		if schainWrapper != nil && len(schainWrapper.Bidders) > 0 {
+			for _, bidder := range schainWrapper.Bidders {
+				if _, present := bidderToSChains[bidder]; present {
+					return nil, fmt.Errorf("request.ext.prebid.schains contains multiple schains for bidder %s; "+
+						"it must contain no more than one per bidder.", bidder)
+				} else {
+					bidderToSChains[bidder] = &schainWrapper.SChain
+				}
+			}
+		}
+	}
+
+	return bidderToSChains, nil
+}
+
 // cleanOpenRTBRequests splits the input request into requests which are sanitized for each bidder. Intended behavior is:
 //
 //   1. BidRequest.Imp[].Ext will only contain the "prebid" field and a "bidder" field which has the params for the intended Bidder.
@@ -103,12 +126,35 @@ func cleanOpenRTBRequests(ctx context.Context,
 	return
 }
 
-func splitBidRequest(req *openrtb.BidRequest, impsByBidder map[string][]openrtb.Imp, aliases map[string]string, usersyncs IdFetcher, blabels map[openrtb_ext.BidderName]*pbsmetrics.AdapterLabels, labels pbsmetrics.Labels) (map[openrtb_ext.BidderName]*openrtb.BidRequest, []error) {
+func splitBidRequest(req *openrtb.BidRequest,
+	impsByBidder map[string][]openrtb.Imp,
+	aliases map[string]string,
+	usersyncs IdFetcher,
+	blabels map[openrtb_ext.BidderName]*pbsmetrics.AdapterLabels,
+	labels pbsmetrics.Labels) (map[openrtb_ext.BidderName]*openrtb.BidRequest, []error) {
+
 	requestsByBidder := make(map[openrtb_ext.BidderName]*openrtb.BidRequest, len(impsByBidder))
 	explicitBuyerUIDs, err := extractBuyerUIDs(req.User)
 	if err != nil {
 		return nil, []error{err}
 	}
+
+	var requestExt openrtb_ext.ExtRequest
+	var sChainsByBidder map[string]*openrtb_ext.ExtRequestPrebidSChainSChain
+	if len(req.Ext) > 0 {
+		err := json.Unmarshal(req.Ext, &requestExt)
+		if err != nil {
+			return nil, []error{err}
+		}
+
+		sChainsByBidder, err = BidderToPrebidSChains(&requestExt)
+		if err != nil {
+			return nil, []error{err}
+		}
+	} else {
+		sChainsByBidder = make(map[string]*openrtb_ext.ExtRequestPrebidSChainSChain)
+	}
+
 	for bidder, imps := range impsByBidder {
 		reqCopy := *req
 		coreBidder := resolveBidder(bidder, aliases)
@@ -128,11 +174,57 @@ func splitBidRequest(req *openrtb.BidRequest, impsByBidder map[string][]openrtb.
 			blabels[coreBidder].CookieFlag = pbsmetrics.CookieFlagYes
 		}
 		reqCopy.Imp = imps
+
+		prepareSource(&reqCopy, bidder, sChainsByBidder)
+		prepareExt(&reqCopy, &requestExt)
+
 		requestsByBidder[openrtb_ext.BidderName(bidder)] = &reqCopy
 	}
 	return requestsByBidder, nil
 }
 
+func prepareExt(req *openrtb.BidRequest, unpackedExt *openrtb_ext.ExtRequest) {
+	if len(req.Ext) == 0 {
+		return
+	}
+	extCopy := *unpackedExt
+	extCopy.Prebid.SChains = nil
+	reqExt, err := json.Marshal(extCopy)
+	if err == nil {
+		req.Ext = reqExt
+	}
+}
+
+func prepareSource(req *openrtb.BidRequest, bidder string, sChainsByBidder map[string]*openrtb_ext.ExtRequestPrebidSChainSChain) {
+	const sChainWildCard = "*"
+	var selectedSChain *openrtb_ext.ExtRequestPrebidSChainSChain
+
+	wildCardSChain := sChainsByBidder[sChainWildCard]
+	bidderSChain := sChainsByBidder[bidder]
+
+	// source should not be modified
+	if bidderSChain == nil && wildCardSChain == nil {
+		return
+	}
+
+	if bidderSChain != nil {
+		selectedSChain = bidderSChain
+	} else {
+		selectedSChain = wildCardSChain
+	}
+
+	// set source
+	var source openrtb.Source
+	schain := openrtb_ext.ExtRequestPrebidSChain{
+		SChain: *selectedSChain,
+	}
+	sourceExt, err := json.Marshal(schain)
+	if err == nil {
+		source.Ext = sourceExt
+		req.Source = &source
+	}
+}
+
 // extractBuyerUIDs parses the values from user.ext.prebid.buyeruids, and then deletes those values from the ext.
 // This prevents a Bidder from using these values to figure out who else is involved in the Auction.
 func extractBuyerUIDs(user *openrtb.User) (map[string]string, error) {
diff --git a/exchange/utils_test.go b/exchange/utils_test.go
index e50d0f777f0..6d66e816e7b 100644
--- a/exchange/utils_test.go
+++ b/exchange/utils_test.go
@@ -135,6 +135,92 @@ func TestCleanOpenRTBRequestsCCPA(t *testing.T) {
 	}
 }
 
+func TestCleanOpenRTBRequestsSChain(t *testing.T) {
+	testCases := []struct {
+		description  string
+		inSourceExt  json.RawMessage
+		inExt        json.RawMessage
+		outSourceExt json.RawMessage
+		outExt       json.RawMessage
+		hasError     bool
+	}{
+		{
+			description:  "Empty root ext and source ext",
+			inSourceExt:  json.RawMessage(``),
+			inExt:        json.RawMessage(``),
+			outSourceExt: json.RawMessage(``),
+			outExt:       json.RawMessage(``),
+			hasError:     false,
+		},
+		{
+			description:  "No schains in root ext and empty source ext",
+			inSourceExt:  json.RawMessage(``),
+			inExt:        json.RawMessage(`{"prebid":{"schains":[]}}`),
+			outSourceExt: json.RawMessage(``),
+			outExt:       json.RawMessage(`{"prebid":{}}`),
+			hasError:     false,
+		},
+		{
+			description:  "Use source schain -- no bidder schain or wildcard schain in ext.prebid.schains",
+			inSourceExt:  json.RawMessage(`{"schain":{"complete":1,"nodes":[{"asi":"example.com","sid":"example1","rid":"ExampleReq1","hp":1}],"ver":"1.0"}}`),
+			inExt:        json.RawMessage(`{"prebid":{"schains":[{"bidders":["bidder1"],"schain":{"complete":1,"nodes":[{"asi":"directseller.com","sid":"00001","rid":"BidRequest1","hp":1}],"ver":"1.0"}}]}}`),
+			outSourceExt: json.RawMessage(`{"schain":{"complete":1,"nodes":[{"asi":"example.com","sid":"example1","rid":"ExampleReq1","hp":1}],"ver":"1.0"}}`),
+			outExt:       json.RawMessage(`{"prebid":{}}`),
+			hasError:     false,
+		},
+		{
+			description:  "Use schain for bidder in ext.prebid.schains",
+			inSourceExt:  json.RawMessage(``),
+			inExt:        json.RawMessage(`{"prebid":{"schains":[{"bidders":["appnexus"],"schain":{"complete":1,"nodes":[{"asi":"directseller.com","sid":"00001","rid":"BidRequest1","hp":1}],"ver":"1.0"}}]}}`),
+			outSourceExt: json.RawMessage(`{"schain":{"complete":1,"nodes":[{"asi":"directseller.com","sid":"00001","rid":"BidRequest1","hp":1}],"ver":"1.0"}}`),
+			outExt:       json.RawMessage(`{"prebid":{}}`),
+			hasError:     false,
+		},
+		{
+			description:  "Use wildcard schain in ext.prebid.schains",
+			inSourceExt:  json.RawMessage(``),
+			inExt:        json.RawMessage(`{"prebid":{"schains":[{"bidders":["*"],"schain":{"complete":1,"nodes":[{"asi":"directseller.com","sid":"00001","rid":"BidRequest1","hp":1}],"ver":"1.0"}}]}}`),
+			outSourceExt: json.RawMessage(`{"schain":{"complete":1,"nodes":[{"asi":"directseller.com","sid":"00001","rid":"BidRequest1","hp":1}],"ver":"1.0"}}`),
+			outExt:       json.RawMessage(`{"prebid":{}}`),
+			hasError:     false,
+		},
+		{
+			description:  "Use schain for bidder in ext.prebid.schains instead of wildcard",
+			inSourceExt:  json.RawMessage(``),
+			inExt:        json.RawMessage(`{"prebid":{"aliases":{"appnexus":"alias1"},"schains":[{"bidders":["appnexus"],"schain":{"complete":1,"nodes":[{"asi":"directseller.com","sid":"00001","rid":"BidRequest1","hp":1}],"ver":"1.0"}}, {"bidders":["*"],"schain":{"complete":1,"nodes":[{"asi":"wildcard.com","sid":"wildcard1","rid":"WildcardReq1","hp":1}],"ver":"1.0"}} ]}}`),
+			outSourceExt: json.RawMessage(`{"schain":{"complete":1,"nodes":[{"asi":"directseller.com","sid":"00001","rid":"BidRequest1","hp":1}],"ver":"1.0"}}`),
+			outExt:       json.RawMessage(`{"prebid":{"aliases":{"appnexus":"alias1"}}}`),
+			hasError:     false,
+		},
+		{
+			description:  "Use source schain -- multiple (two) bidder schains in ext.prebid.schains",
+			inSourceExt:  json.RawMessage(`{"schain":{"complete":1,"nodes":[{"asi":"example.com","sid":"example1","rid":"ExampleReq1","hp":1}],"ver":"1.0"}}`),
+			inExt:        json.RawMessage(`{"prebid":{"schains":[{"bidders":["appnexus"],"schain":{"complete":1,"nodes":[{"asi":"directseller1.com","sid":"00001","rid":"BidRequest1","hp":1}],"ver":"1.0"}}, {"bidders":["appnexus"],"schain":{"complete":1,"nodes":[{"asi":"directseller2.com","sid":"00002","rid":"BidRequest2","hp":1}],"ver":"1.0"}}]}}`),
+			outSourceExt: nil,
+			outExt:       nil,
+			hasError:     true,
+		},
+	}
+
+	for _, test := range testCases {
+		req := newBidRequest(t)
+		req.Source.Ext = test.inSourceExt
+		req.Ext = test.inExt
+
+		results, _, _, errs := cleanOpenRTBRequests(context.Background(), req, &emptyUsersync{}, map[openrtb_ext.BidderName]*pbsmetrics.AdapterLabels{}, pbsmetrics.Labels{}, &permissionsMock{}, true, config.Privacy{})
+		result := results["appnexus"]
+
+		if test.hasError == true {
+			assert.NotNil(t, errs)
+			assert.Nil(t, result)
+		} else {
+			assert.Nil(t, errs)
+			assert.Equal(t, test.outSourceExt, result.Source.Ext, test.description+":Source.Ext")
+			assert.Equal(t, test.outExt, result.Ext, test.description+":Ext")
+		}
+	}
+}
+
 func TestCleanOpenRTBRequestsLMT(t *testing.T) {
 	var (
 		enabled  int8 = 1
@@ -302,5 +388,99 @@ func TestRandomizeList(t *testing.T) {
 	if len(adapters) != 1 {
 		t.Errorf("RandomizeList, expected a list of 1, found %d", len(adapters))
 	}
+}
+
+func TestBidderToPrebidChains(t *testing.T) {
+	input := openrtb_ext.ExtRequest{
+		Prebid: openrtb_ext.ExtRequestPrebid{
+			SChains: []*openrtb_ext.ExtRequestPrebidSChain{
+				{
+					Bidders: []string{"Bidder1", "Bidder2"},
+					SChain: openrtb_ext.ExtRequestPrebidSChainSChain{
+						Complete: 1,
+						Nodes: []*openrtb_ext.ExtRequestPrebidSChainSChainNode{
+							{
+								ASI:    "asi1",
+								SID:    "sid1",
+								Name:   "name1",
+								RID:    "rid1",
+								Domain: "domain1",
+								HP:     1,
+							},
+							{
+								ASI:    "asi2",
+								SID:    "sid2",
+								Name:   "name2",
+								RID:    "rid2",
+								Domain: "domain2",
+								HP:     2,
+							},
+						},
+						Ver: "version1",
+					},
+				},
+				{
+					Bidders: []string{"Bidder3", "Bidder4"},
+					SChain:  openrtb_ext.ExtRequestPrebidSChainSChain{},
+				},
+			},
+		},
+	}
+
+	output, err := BidderToPrebidSChains(&input)
+
+	assert.Nil(t, err)
+	assert.Equal(t, len(output), 4)
+	assert.Same(t, output["Bidder1"], &input.Prebid.SChains[0].SChain)
+	assert.Same(t, output["Bidder2"], &input.Prebid.SChains[0].SChain)
+	assert.Same(t, output["Bidder3"], &input.Prebid.SChains[1].SChain)
+	assert.Same(t, output["Bidder4"], &input.Prebid.SChains[1].SChain)
+}
+
+func TestBidderToPrebidChainsDiscardMultipleChainsForBidder(t *testing.T) {
+	input := openrtb_ext.ExtRequest{
+		Prebid: openrtb_ext.ExtRequestPrebid{
+			SChains: []*openrtb_ext.ExtRequestPrebidSChain{
+				{
+					Bidders: []string{"Bidder1"},
+					SChain:  openrtb_ext.ExtRequestPrebidSChainSChain{},
+				},
+				{
+					Bidders: []string{"Bidder1", "Bidder2"},
+					SChain:  openrtb_ext.ExtRequestPrebidSChainSChain{},
+				},
+			},
+		},
+	}
+
+	output, err := BidderToPrebidSChains(&input)
+
+	assert.NotNil(t, err)
+	assert.Nil(t, output)
+}
+
+func TestBidderToPrebidChainsNilSChains(t *testing.T) {
+	input := openrtb_ext.ExtRequest{
+		Prebid: openrtb_ext.ExtRequestPrebid{
+			SChains: nil,
+		},
+	}
+
+	output, err := BidderToPrebidSChains(&input)
+
+	assert.Nil(t, err)
+	assert.Equal(t, len(output), 0)
+}
+
+func TestBidderToPrebidChainsZeroLengthSChains(t *testing.T) {
+	input := openrtb_ext.ExtRequest{
+		Prebid: openrtb_ext.ExtRequestPrebid{
+			SChains: []*openrtb_ext.ExtRequestPrebidSChain{},
+		},
+	}
+
+	output, err := BidderToPrebidSChains(&input)
 
+	assert.Nil(t, err)
+	assert.Equal(t, len(output), 0)
 }
diff --git a/openrtb_ext/request.go b/openrtb_ext/request.go
index 25b5c881408..86388f60cf4 100644
--- a/openrtb_ext/request.go
+++ b/openrtb_ext/request.go
@@ -12,12 +12,43 @@ type ExtRequest struct {
 
 // ExtRequestPrebid defines the contract for bidrequest.ext.prebid
 type ExtRequestPrebid struct {
-	Aliases              map[string]string      `json:"aliases,omitempty"`
-	BidAdjustmentFactors map[string]float64     `json:"bidadjustmentfactors,omitempty"`
-	Cache                *ExtRequestPrebidCache `json:"cache,omitempty"`
-	StoredRequest        *ExtStoredRequest      `json:"storedrequest,omitempty"`
-	Targeting            *ExtRequestTargeting   `json:"targeting,omitempty"`
-	SupportDeals         bool                   `json:"supportdeals,omitempty"`
+	Aliases              map[string]string         `json:"aliases,omitempty"`
+	BidAdjustmentFactors map[string]float64        `json:"bidadjustmentfactors,omitempty"`
+	Cache                *ExtRequestPrebidCache    `json:"cache,omitempty"`
+	SChains              []*ExtRequestPrebidSChain `json:"schains,omitempty"`
+	StoredRequest        *ExtStoredRequest         `json:"storedrequest,omitempty"`
+	Targeting            *ExtRequestTargeting      `json:"targeting,omitempty"`
+	SupportDeals         bool                      `json:"supportdeals,omitempty"`
+}
+
+// ExtRequestPrebid defines the contract for bidrequest.ext.prebid.schains
+type ExtRequestPrebidSChain struct {
+	Bidders []string                     `json:"bidders,omitempty"`
+	SChain  ExtRequestPrebidSChainSChain `json:"schain"`
+}
+
+// ExtRequestPrebidSChainSChain defines the contract for bidrequest.ext.prebid.schains[i].schain
+type ExtRequestPrebidSChainSChain struct {
+	Complete int                                 `json:"complete"`
+	Nodes    []*ExtRequestPrebidSChainSChainNode `json:"nodes"`
+	Ver      string                              `json:"ver"`
+	Ext      json.RawMessage                     `json:"ext,omitempty"`
+}
+
+// ExtRequestPrebidSChainSChainNode defines the contract for bidrequest.ext.prebid.schains[i].schain[i].nodes
+type ExtRequestPrebidSChainSChainNode struct {
+	ASI    string          `json:"asi"`
+	SID    string          `json:"sid"`
+	RID    string          `json:"rid,omitempty"`
+	Name   string          `json:"name,omitempty"`
+	Domain string          `json:"domain,omitempty"`
+	HP     int             `json:"hp"`
+	Ext    json.RawMessage `json:"ext,omitempty"`
+}
+
+// SourceExt defines the contract for bidrequest.source.ext
+type SourceExt struct {
+	SChain ExtRequestPrebidSChainSChain `json:"schain"`
 }
 
 // ExtRequestPrebidCache defines the contract for bidrequest.ext.prebid.cache