diff --git a/modules/sharethroughBidAdapter.js b/modules/sharethroughBidAdapter.js
index bb7f778089a..9aabca9518a 100644
--- a/modules/sharethroughBidAdapter.js
+++ b/modules/sharethroughBidAdapter.js
@@ -1,12 +1,14 @@
 import { registerBidder } from 'src/adapters/bidderFactory';
 
+const VERSION = '3.0.0';
 const BIDDER_CODE = 'sharethrough';
-const VERSION = '2.0.0';
 const STR_ENDPOINT = document.location.protocol + '//btlr.sharethrough.com/header-bid/v1';
 
 export const sharethroughAdapterSpec = {
   code: BIDDER_CODE,
+
   isBidRequestValid: bid => !!bid.params.pkey && bid.bidder === BIDDER_CODE,
+
   buildRequests: (bidRequests, bidderRequest) => {
     return bidRequests.map(bid => {
       let query = {
@@ -26,67 +28,112 @@ export const sharethroughAdapterSpec = {
         query.consent_required = !!bidderRequest.gdprConsent.gdprApplies;
       }
 
+      // Data that does not need to go to the server,
+      // but we need as part of interpretResponse()
+      const strData = {
+        stayInIframe: bid.params.iframe,
+        sizes: bid.sizes
+      }
+
       return {
         method: 'GET',
         url: STR_ENDPOINT,
-        data: query
+        data: query,
+        strData: strData
       };
     })
   },
+
   interpretResponse: ({ body }, req) => {
-    if (!body || !Object.keys(body).length || !body.creatives.length) {
+    if (!body || !body.creatives || !body.creatives.length) {
       return [];
     }
 
     const creative = body.creatives[0];
+    let size = [0, 0];
+    if (req.strData.stayInIframe) {
+      size = getLargestSize(req.strData.sizes);
+    }
 
     return [{
       requestId: req.data.bidId,
-      width: 0,
-      height: 0,
+      width: size[0],
+      height: size[1],
       cpm: creative.cpm,
       creativeId: creative.creative.creative_key,
-      deal_id: creative.creative.deal_id,
+      dealId: creative.creative.deal_id,
       currency: 'USD',
       netRevenue: true,
       ttl: 360,
       ad: generateAd(body, req)
     }];
   },
+
   getUserSyncs: (syncOptions, serverResponses) => {
     const syncs = [];
-    if (syncOptions.pixelEnabled && serverResponses.length > 0 && serverResponses[0].body) {
+    const shouldCookieSync = syncOptions.pixelEnabled &&
+                             serverResponses.length > 0 &&
+                             serverResponses[0].body &&
+                             serverResponses[0].body.cookieSyncUrls;
+
+    if (shouldCookieSync) {
       serverResponses[0].body.cookieSyncUrls.forEach(url => {
         syncs.push({ type: 'image', url: url });
       });
     }
+
     return syncs;
   }
 }
 
+function getLargestSize(sizes) {
+  function area(size) {
+    return size[0] * size[1];
+  }
+
+  return sizes.reduce((prev, current) => {
+    if (area(current) > area(prev)) {
+      return current
+    } else {
+      return prev
+    }
+  }, [0, 0]);
+}
+
 function generateAd(body, req) {
   const strRespId = `str_response_${req.data.bidId}`;
 
-  return `
+  let adMarkup = `
     <div data-str-native-key="${req.data.placement_key}" data-stx-response-name="${strRespId}">
     </div>
     <script>var ${strRespId} = "${b64EncodeUnicode(JSON.stringify(body))}"</script>
-    <script src="//native.sharethrough.com/assets/sfp-set-targeting.js"></script>
-    <script>
-    (function() {
-      if (!(window.STR && window.STR.Tag) && !(window.top.STR && window.top.STR.Tag)) {
-        const sfp_js = document.createElement('script');
-        sfp_js.src = "//native.sharethrough.com/assets/sfp.js";
-        sfp_js.type = 'text/javascript';
-        sfp_js.charset = 'utf-8';
-        try {
-            window.top.document.getElementsByTagName('body')[0].appendChild(sfp_js);
-        } catch (e) {
-          console.log(e);
-        }
-      }
-    })()
-    </script>`;
+  `
+
+  if (req.strData.stayInIframe) {
+    // Don't break out of iframe
+    adMarkup = adMarkup + `<script src="//native.sharethrough.com/assets/sfp.js"></script>`
+  } else {
+    // Break out of iframe
+    adMarkup = adMarkup + `
+      <script src="//native.sharethrough.com/assets/sfp-set-targeting.js"></script>
+      <script>
+        (function() {
+          if (!(window.STR && window.STR.Tag) && !(window.top.STR && window.top.STR.Tag)) {
+            const sfp_js = document.createElement('script');
+            sfp_js.src = "//native.sharethrough.com/assets/sfp.js";
+            sfp_js.type = 'text/javascript';
+            sfp_js.charset = 'utf-8';
+            try {
+                window.top.document.getElementsByTagName('body')[0].appendChild(sfp_js);
+            } catch (e) {
+              console.log(e);
+            }
+          }
+        })()
+    </script>`
+  }
+
+  return adMarkup;
 }
 
 // See https://developer.mozilla.org/en-US/docs/Web/API/WindowBase64/Base64_encoding_and_decoding#The_Unicode_Problem
diff --git a/modules/sharethroughBidAdapter.md b/modules/sharethroughBidAdapter.md
index 8ab44f2a0f2..d2d8030c5f7 100644
--- a/modules/sharethroughBidAdapter.md
+++ b/modules/sharethroughBidAdapter.md
@@ -26,12 +26,13 @@ Module that connects to Sharethrough's demand sources
                ]
            },{
                code: 'test-div',
-               sizes: [[1, 1]],   // a mobile size
+               sizes: [[300,250], [1, 1]],   // a mobile size
                bids: [
                    {
                        bidder: "sharethrough",
                        params: {
-                           pkey: 'LuB3vxGGFrBZJa6tifXW4xgK'
+                           pkey: 'LuB3vxGGFrBZJa6tifXW4xgK',
+                           iframe: true
                        }
                    }
                ]
diff --git a/test/spec/modules/sharethroughBidAdapter_spec.js b/test/spec/modules/sharethroughBidAdapter_spec.js
index 2aef88fe7eb..a599ce6cdc8 100644
--- a/test/spec/modules/sharethroughBidAdapter_spec.js
+++ b/test/spec/modules/sharethroughBidAdapter_spec.js
@@ -19,17 +19,38 @@ const bidderRequest = [
     sizes: [[700, 400]],
     placementCode: 'bar',
     params: {
-      pkey: 'bbbb2222'
+      pkey: 'bbbb2222',
+      iframe: true
     }
   }];
-const prebidRequest = [{
-  method: 'GET',
-  url: document.location.protocol + '//btlr.sharethrough.com' + '/header-bid/v1',
-  data: {
-    bidId: 'bidId',
-    placement_key: 'pKey'
-  }
-}];
+
+const prebidRequests = [
+  {
+    method: 'GET',
+    url: document.location.protocol + '//btlr.sharethrough.com' + '/header-bid/v1',
+    data: {
+      bidId: 'bidId',
+      placement_key: 'pKey'
+    },
+    strData: {
+      stayInIframe: false,
+      sizes: []
+    }
+  },
+  {
+    method: 'GET',
+    url: document.location.protocol + '//btlr.sharethrough.com' + '/header-bid/v1',
+    data: {
+      bidId: 'bidId',
+      placement_key: 'pKey'
+    },
+    strData: {
+      stayInIframe: true,
+      sizes: [[300, 250], [300, 300], [250, 250], [600, 50]]
+    }
+  },
+];
+
 const bidderResponse = {
   body: {
     'adserverRequestId': '40b6afd5-6134-4fbb-850a-bb8972a46994',
@@ -48,6 +69,7 @@ const bidderResponse = {
   },
   header: { get: (header) => header }
 };
+
 // Mirrors the one in modules/sharethroughBidAdapter.js as the function is unexported
 const b64EncodeUnicode = (str) => {
   return btoa(
@@ -56,6 +78,7 @@ const b64EncodeUnicode = (str) => {
         return String.fromCharCode('0x' + p1);
       }));
 }
+
 describe('sharethrough adapter spec', () => {
   describe('.code', () => {
     it('should return a bidder code of sharethrough', () => {
@@ -119,13 +142,27 @@ describe('sharethrough adapter spec', () => {
 
   describe('.interpretResponse', () => {
     it('returns a correctly parsed out response', () => {
-      expect(spec.interpretResponse(bidderResponse, prebidRequest[0])[0]).to.include(
+      expect(spec.interpretResponse(bidderResponse, prebidRequests[0])[0]).to.include(
         {
           width: 0,
           height: 0,
           cpm: 12.34,
           creativeId: 'aCreativeId',
-          deal_id: 'aDealId',
+          dealId: 'aDealId',
+          currency: 'USD',
+          netRevenue: true,
+          ttl: 360,
+        });
+    });
+
+    it('returns a correctly parsed out response with largest size when strData.stayInIframe is true', () => {
+      expect(spec.interpretResponse(bidderResponse, prebidRequests[1])[0]).to.include(
+        {
+          width: 300,
+          height: 300,
+          cpm: 12.34,
+          creativeId: 'aCreativeId',
+          dealId: 'aDealId',
           currency: 'USD',
           netRevenue: true,
           ttl: 360,
@@ -134,21 +171,21 @@ describe('sharethrough adapter spec', () => {
 
     it('returns a blank array if there are no creatives', () => {
       const bidResponse = { body: { creatives: [] } };
-      expect(spec.interpretResponse(bidResponse, prebidRequest[0])).to.be.an('array').that.is.empty;
+      expect(spec.interpretResponse(bidResponse, prebidRequests[0])).to.be.an('array').that.is.empty;
     });
 
     it('returns a blank array if body object is empty', () => {
       const bidResponse = { body: {} };
-      expect(spec.interpretResponse(bidResponse, prebidRequest[0])).to.be.an('array').that.is.empty;
+      expect(spec.interpretResponse(bidResponse, prebidRequests[0])).to.be.an('array').that.is.empty;
     });
 
     it('returns a blank array if body is null', () => {
       const bidResponse = { body: null };
-      expect(spec.interpretResponse(bidResponse, prebidRequest[0])).to.be.an('array').that.is.empty;
+      expect(spec.interpretResponse(bidResponse, prebidRequests[0])).to.be.an('array').that.is.empty;
     });
 
-    it('correctly sends back a sfp script tag', () => {
-      const adMarkup = spec.interpretResponse(bidderResponse, prebidRequest[0])[0].ad;
+    it('correctly generates ad markup', () => {
+      const adMarkup = spec.interpretResponse(bidderResponse, prebidRequests[0])[0].ad;
       let resp = null;
 
       expect(() => btoa(JSON.stringify(bidderResponse))).to.throw();
@@ -163,6 +200,19 @@ describe('sharethrough adapter spec', () => {
       expect(adMarkup).to.match(
         /window.top.document.getElementsByTagName\('body'\)\[0\].appendChild\(sfp_js\);/)
     });
+
+    it('correctly generates ad markup for staying in iframe', () => {
+      const adMarkup = spec.interpretResponse(bidderResponse, prebidRequests[1])[0].ad;
+      let resp = null;
+
+      expect(() => btoa(JSON.stringify(bidderResponse))).to.throw();
+      expect(() => resp = b64EncodeUnicode(JSON.stringify(bidderResponse))).not.to.throw();
+      expect(adMarkup).to.match(
+        /data-str-native-key="pKey" data-stx-response-name=\"str_response_bidId\"/);
+      expect(!!adMarkup.indexOf(resp)).to.eql(true);
+      expect(adMarkup).to.match(
+        /<script src="\/\/native.sharethrough.com\/assets\/sfp.js"><\/script>/);
+    });
   });
 
   describe('.getUserSyncs', () => {
@@ -183,6 +233,11 @@ describe('sharethrough adapter spec', () => {
       expect(syncArray).to.be.an('array').that.is.empty;
     });
 
+    it('returns an empty array if the body.cookieSyncUrls is missing', () => {
+      const syncArray = spec.getUserSyncs({ pixelEnabled: true }, [{ body: { creatives: ['creative'] } }]);
+      expect(syncArray).to.be.an('array').that.is.empty;
+    });
+
     it('returns an empty array if pixels are not enabled', () => {
       const syncArray = spec.getUserSyncs({ pixelEnabled: false }, serverResponses);
       expect(syncArray).to.be.an('array').that.is.empty;