diff --git a/src/adaptermanager.js b/src/adaptermanager.js
index 8aefc67cad4..c6568c0c9f7 100644
--- a/src/adaptermanager.js
+++ b/src/adaptermanager.js
@@ -1,7 +1,7 @@
 /** @module adaptermanger */
 
 import { flatten, getBidderCodes, getDefinedParams, shuffle } from './utils';
-import { mapSizes } from './sizeMapping';
+import { resolveStatus } from './sizeMapping';
 import { processNativeAdUnitParams, nativeAdapters } from './native';
 import { newBidder } from './adapters/bidderFactory';
 import { ajaxBuilder } from 'src/ajax';
@@ -19,53 +19,74 @@ let _s2sConfig = config.getConfig('s2sConfig');
 
 var _analyticsRegistry = {};
 
-function getBids({bidderCode, auctionId, bidderRequestId, adUnits}) {
-  return adUnits.map(adUnit => {
-    return adUnit.bids.filter(bid => bid.bidder === bidderCode)
-      .map(bid => {
-        let sizes = adUnit.sizes;
-        if (adUnit.sizeMapping) {
-          let sizeMapping = mapSizes(adUnit);
-          if (sizeMapping === '') {
-            return '';
-          }
-          sizes = sizeMapping;
-        }
+/**
+ * @typedef {object} LabelDescriptor
+ * @property {boolean} labelAll describes whether or not this object expects all labels to match, or any label to match
+ * @property {Array<string>} labels the labels listed on the bidder or adUnit
+ * @property {Array<string>} activeLabels the labels specified as being active by requestBids
+ */
+
+/**
+ * Returns object describing the status of labels on the adUnit or bidder along with labels passed into requestBids
+ * @param bidOrAdUnit the bidder or adUnit to get label info on
+ * @param activeLabels the labels passed to requestBids
+ * @returns {LabelDescriptor}
+ */
+function getLabels(bidOrAdUnit, activeLabels) {
+  if (bidOrAdUnit.labelAll) {
+    return {labelAll: true, labels: bidOrAdUnit.labelAll, activeLabels};
+  }
+  return {labelAll: false, labels: bidOrAdUnit.labelAny, activeLabels};
+}
 
-        if (adUnit.mediaTypes) {
-          if (utils.isValidMediaTypes(adUnit.mediaTypes)) {
-            bid = Object.assign({}, bid, { mediaTypes: adUnit.mediaTypes });
-          } else {
-            utils.logError(
-              `mediaTypes is not correctly configured for adunit ${adUnit.code}`
-            );
+function getBids({bidderCode, auctionId, bidderRequestId, adUnits, labels}) {
+  return adUnits.reduce((result, adUnit) => {
+    let {active, sizes: filteredAdUnitSizes} = resolveStatus(getLabels(adUnit, labels), adUnit.sizes);
+
+    if (active) {
+      result.push(adUnit.bids.filter(bid => bid.bidder === bidderCode)
+        .reduce((bids, bid) => {
+          if (adUnit.mediaTypes) {
+            if (utils.isValidMediaTypes(adUnit.mediaTypes)) {
+              bid = Object.assign({}, bid, {mediaTypes: adUnit.mediaTypes});
+            } else {
+              utils.logError(
+                `mediaTypes is not correctly configured for adunit ${adUnit.code}`
+              );
+            }
           }
-        }
 
-        const nativeParams =
-          adUnit.nativeParams || utils.deepAccess(adUnit, 'mediaTypes.native');
-        if (nativeParams) {
-          bid = Object.assign({}, bid, {
-            nativeParams: processNativeAdUnitParams(nativeParams),
-          });
-        }
+          const nativeParams =
+            adUnit.nativeParams || utils.deepAccess(adUnit, 'mediaTypes.native');
+          if (nativeParams) {
+            bid = Object.assign({}, bid, {
+              nativeParams: processNativeAdUnitParams(nativeParams),
+            });
+          }
 
-        bid = Object.assign({}, bid, getDefinedParams(adUnit, [
-          'mediaType',
-          'renderer'
-        ]));
-
-        return Object.assign({}, bid, {
-          adUnitCode: adUnit.code,
-          transactionId: adUnit.transactionId,
-          sizes: sizes,
-          bidId: bid.bid_id || utils.getUniqueIdentifierStr(),
-          bidderRequestId,
-          auctionId
-        });
-      }
+          bid = Object.assign({}, bid, getDefinedParams(adUnit, [
+            'mediaType',
+            'renderer'
+          ]));
+
+          let {active, sizes} = resolveStatus(getLabels(bid, labels), filteredAdUnitSizes);
+
+          if (active) {
+            bids.push(Object.assign({}, bid, {
+              adUnitCode: adUnit.code,
+              transactionId: adUnit.transactionId,
+              sizes: sizes,
+              bidId: bid.bid_id || utils.getUniqueIdentifierStr(),
+              bidderRequestId,
+              auctionId
+            }));
+          }
+          return bids;
+        }, [])
       );
-  }).reduce(flatten, []).filter(val => val !== '');
+    }
+    return result;
+  }, []).reduce(flatten, []).filter(val => val !== '');
 }
 
 function getAdUnitCopyForPrebidServer(adUnits) {
@@ -94,7 +115,7 @@ function getAdUnitCopyForPrebidServer(adUnits) {
   return adUnitsCopy;
 }
 
-exports.makeBidRequests = function(adUnits, auctionStart, auctionId, cbTimeout) {
+exports.makeBidRequests = function(adUnits, auctionStart, auctionId, cbTimeout, labels) {
   let bidRequests = [];
   let bidderCodes = getBidderCodes(adUnits);
   if (config.getConfig('bidderSequence') === RANDOM) {
@@ -134,7 +155,7 @@ exports.makeBidRequests = function(adUnits, auctionStart, auctionId, cbTimeout)
         auctionId,
         bidderRequestId,
         tid,
-        bids: getBids({bidderCode, auctionId, bidderRequestId, 'adUnits': adUnitsS2SCopy}),
+        bids: getBids({bidderCode, auctionId, bidderRequestId, 'adUnits': adUnitsS2SCopy, labels}),
         auctionStart: auctionStart,
         timeout: _s2sConfig.timeout,
         src: CONSTANTS.S2S.SRC
@@ -165,7 +186,7 @@ exports.makeBidRequests = function(adUnits, auctionStart, auctionId, cbTimeout)
       bidderCode,
       auctionId,
       bidderRequestId,
-      bids: getBids({bidderCode, auctionId, bidderRequestId, adUnits}),
+      bids: getBids({bidderCode, auctionId, bidderRequestId, adUnits, labels}),
       auctionStart: auctionStart,
       timeout: cbTimeout
     };
@@ -174,7 +195,7 @@ exports.makeBidRequests = function(adUnits, auctionStart, auctionId, cbTimeout)
     }
   });
   return bidRequests;
-}
+};
 
 exports.callBids = (adUnits, bidRequests, addBidResponse, doneCb) => {
   let serverBidRequests = bidRequests.filter(bidRequest => {
@@ -194,22 +215,26 @@ exports.callBids = (adUnits, bidRequests, addBidResponse, doneCb) => {
       }
     }
   }
-  let ajax = ajaxBuilder(bidRequests[0].timeout);
-  bidRequests.forEach(bidRequest => {
-    bidRequest.start = new Date().getTime();
-    // TODO : Do we check for bid in pool from here and skip calling adapter again ?
-    const adapter = _bidderRegistry[bidRequest.bidderCode];
-    if (adapter) {
-      utils.logMessage(`CALLING BIDDER ======= ${bidRequest.bidderCode}`);
-      events.emit(CONSTANTS.EVENTS.BID_REQUESTED, bidRequest);
-      bidRequest.doneCbCallCount = 0;
-      let done = doneCb(bidRequest.bidderRequestId);
-      adapter.callBids(bidRequest, addBidResponse, done, ajax);
-    } else {
-      utils.logError(`Adapter trying to be called which does not exist: ${bidRequest.bidderCode} adaptermanager.callBids`);
-    }
-  });
-}
+  if (bidRequests.length) {
+    let ajax = ajaxBuilder(bidRequests[0].timeout);
+    bidRequests.forEach(bidRequest => {
+      bidRequest.start = new Date().getTime();
+      // TODO : Do we check for bid in pool from here and skip calling adapter again ?
+      const adapter = _bidderRegistry[bidRequest.bidderCode];
+      if (adapter) {
+        utils.logMessage(`CALLING BIDDER ======= ${bidRequest.bidderCode}`);
+        events.emit(CONSTANTS.EVENTS.BID_REQUESTED, bidRequest);
+        bidRequest.doneCbCallCount = 0;
+        let done = doneCb(bidRequest.bidderRequestId);
+        adapter.callBids(bidRequest, addBidResponse, done, ajax);
+      } else {
+        utils.logError(`Adapter trying to be called which does not exist: ${bidRequest.bidderCode} adaptermanager.callBids`);
+      }
+    });
+  } else {
+    utils.logWarn('callBids executed with no bidRequests.  Were they filtered by labels or sizing?');
+  }
+};
 
 function transformHeightWidth(adUnit) {
   let sizesObj = [];
diff --git a/src/auction.js b/src/auction.js
index 36f1d4ed27b..17ce9dbfc46 100644
--- a/src/auction.js
+++ b/src/auction.js
@@ -82,8 +82,9 @@ events.on(CONSTANTS.EVENTS.BID_ADJUSTMENT, function (bid) {
   *
   * @returns {Auction} auction instance
   */
-export function newAuction({adUnits, adUnitCodes, callback, cbTimeout}) {
+export function newAuction({adUnits, adUnitCodes, callback, cbTimeout, labels}) {
   let _adUnits = adUnits;
+  let _labels = labels;
   let _adUnitCodes = adUnitCodes;
   let _bidderRequests = [];
   let _bidsReceived = [];
@@ -346,7 +347,7 @@ export function newAuction({adUnits, adUnitCodes, callback, cbTimeout}) {
     };
     events.emit(CONSTANTS.EVENTS.AUCTION_INIT, auctionInit);
 
-    let bidRequests = adaptermanager.makeBidRequests(_adUnits, _auctionStart, _auctionId, _timeout);
+    let bidRequests = adaptermanager.makeBidRequests(_adUnits, _auctionStart, _auctionId, _timeout, _labels);
     utils.logInfo(`Bids Requested for Auction with id: ${_auctionId}`, bidRequests);
     bidRequests.forEach(bidRequest => {
       addBidRequests(bidRequest);
diff --git a/src/auctionManager.js b/src/auctionManager.js
index 5ca415d29c9..ba6439e3792 100644
--- a/src/auctionManager.js
+++ b/src/auctionManager.js
@@ -60,8 +60,8 @@ export function newAuctionManager() {
       .filter(uniques);
   };
 
-  _public.createAuction = function({ adUnits, adUnitCodes, callback, cbTimeout }) {
-    const auction = newAuction({ adUnits, adUnitCodes, callback, cbTimeout })
+  _public.createAuction = function({ adUnits, adUnitCodes, callback, cbTimeout, labels }) {
+    const auction = newAuction({ adUnits, adUnitCodes, callback, cbTimeout, labels });
     _addAuction(auction);
     return auction;
   };
diff --git a/src/prebid.js b/src/prebid.js
index b38b66d150e..bfd383002d1 100644
--- a/src/prebid.js
+++ b/src/prebid.js
@@ -296,9 +296,10 @@ $$PREBID_GLOBAL$$.removeAdUnit = function (adUnitCode) {
  * @param {number} requestOptions.timeout
  * @param {Array} requestOptions.adUnits
  * @param {Array} requestOptions.adUnitCodes
+ * @param {Array} requestOptions.labels
  * @alias module:pbjs.requestBids
  */
-$$PREBID_GLOBAL$$.requestBids = function ({ bidsBackHandler, timeout, adUnits, adUnitCodes } = {}) {
+$$PREBID_GLOBAL$$.requestBids = function ({ bidsBackHandler, timeout, adUnits, adUnitCodes, labels } = {}) {
   events.emit('requestBids');
   const cbTimeout = timeout || config.getConfig('bidderTimeout');
   adUnits = adUnits || $$PREBID_GLOBAL$$.adUnits;
@@ -346,7 +347,7 @@ $$PREBID_GLOBAL$$.requestBids = function ({ bidsBackHandler, timeout, adUnits, a
     return;
   }
 
-  const auction = auctionManager.createAuction({adUnits, adUnitCodes, callback: bidsBackHandler, cbTimeout});
+  const auction = auctionManager.createAuction({adUnits, adUnitCodes, callback: bidsBackHandler, cbTimeout, labels});
   auction.callBids();
 };
 
diff --git a/src/sizeMapping.js b/src/sizeMapping.js
index 9529c567308..6238df6cd26 100644
--- a/src/sizeMapping.js
+++ b/src/sizeMapping.js
@@ -1,61 +1,84 @@
+import { config } from 'src/config';
+
+let sizeConfig = [];
+
 /**
- * @module sizeMapping
+ * @typedef {object} SizeConfig
+ *
+ * @property {string} [mediaQuery] A CSS media query string that will to be interpreted by window.matchMedia.  If the
+ *  media query matches then the this config will be active and sizesSupported will filter bid and adUnit sizes.  If
+ *  this property is not present then this SizeConfig will only be active if triggered manually by a call to
+ *  pbjs.setConfig({labels:['label']) specifying one of the labels present on this SizeConfig.
+ * @property {Array<Array>} sizesSupported The sizes to be accepted if this SizeConfig is enabled.
+ * @property {Array<string>} labels The active labels to match this SizeConfig to an adUnits and/or bidders.
  */
-import * as utils from './utils';
-let _win;
-
-function mapSizes(adUnit) {
-  if (!isSizeMappingValid(adUnit.sizeMapping)) {
-    return adUnit.sizes;
-  }
-  const width = getScreenWidth();
-  if (!width) {
-    // size not detected - get largest value set for desktop
-    const mapping = adUnit.sizeMapping.reduce((prev, curr) => {
-      return prev.minWidth < curr.minWidth ? curr : prev;
-    });
-    if (mapping.sizes && mapping.sizes.length) {
-      return mapping.sizes;
-    }
-    return adUnit.sizes;
-  }
-  let sizes = '';
-  const mapping = adUnit.sizeMapping.find(sizeMapping => {
-    return width >= sizeMapping.minWidth;
-  });
-  if (mapping && mapping.sizes && mapping.sizes.length) {
-    sizes = mapping.sizes;
-    utils.logMessage(`AdUnit : ${adUnit.code} resized based on device width to : ${sizes}`);
-  } else {
-    utils.logMessage(`AdUnit : ${adUnit.code} not mapped to any sizes for device width. This request will be suppressed.`);
-  }
-  return sizes;
-}
 
-function isSizeMappingValid(sizeMapping) {
-  if (utils.isArray(sizeMapping) && sizeMapping.length > 0) {
-    return true;
-  }
-  utils.logInfo('No size mapping defined');
-  return false;
+/**
+ *
+ * @param {Array<SizeConfig>} config
+ */
+export function setSizeConfig(config) {
+  sizeConfig = config;
 }
+config.getConfig('sizeConfig', config => setSizeConfig(config.sizeConfig));
 
-function getScreenWidth(win) {
-  var w = win || _win || window;
-  var d = w.document;
+/**
+ * Resolves the unique set of the union of all sizes and labels that are active from a SizeConfig.mediaQuery match
+ * @param {Array<string>} labels Labels specified on adUnit or bidder
+ * @param {boolean} labelAll if true, all labels must match to be enabled
+ * @param {Array<string>} activeLabels Labels passed in through requestBids
+ * @param {Array<Array<number>>} sizes Sizes specified on adUnit
+ * @param {Array<SizeConfig>} configs
+ * @returns {{labels: Array<string>, sizes: Array<Array<number>>}}
+ */
+export function resolveStatus({labels = [], labelAll = false, activeLabels = []} = {}, sizes = [], configs = sizeConfig) {
+  let maps = evaluateSizeConfig(configs);
 
-  if (w.innerWidth) {
-    return w.innerWidth;
-  } else if (d.body.clientWidth) {
-    return d.body.clientWidth;
-  } else if (d.documentElement.clientWidth) {
-    return d.documentElement.clientWidth;
+  let filteredSizes;
+  if (maps.shouldFilter) {
+    filteredSizes = sizes.filter(size => maps.sizesSupported[size]);
+  } else {
+    filteredSizes = sizes;
   }
-  return 0;
-}
 
-function setWindow(win) {
-  _win = win;
+  return {
+    active: filteredSizes.length > 0 && (
+      labels.length === 0 || (
+        (!labelAll && (
+          labels.some(label => maps.labels[label]) ||
+          labels.some(label => activeLabels.includes(label))
+        )) ||
+        (labelAll && (
+          labels.reduce((result, label) => !result ? result : (
+            maps.labels[label] || activeLabels.includes(label)
+          ), true)
+        ))
+      )
+    ),
+    sizes: filteredSizes
+  };
 }
 
-export { mapSizes, getScreenWidth, setWindow };
+function evaluateSizeConfig(configs) {
+  return configs.reduce((results, config) => {
+    if (
+      typeof config === 'object' &&
+      typeof config.mediaQuery === 'string' &&
+      matchMedia(config.mediaQuery).matches
+    ) {
+      if (Array.isArray(config.sizesSupported)) {
+        results.shouldFilter = true;
+      }
+      ['labels', 'sizesSupported'].forEach(
+        type => (config[type] || []).forEach(
+          thing => results[type][thing] = true
+        )
+      );
+    }
+    return results;
+  }, {
+    labels: {},
+    sizesSupported: {},
+    shouldFilter: false
+  });
+}
diff --git a/test/spec/sizeMapping_spec.js b/test/spec/sizeMapping_spec.js
index 471d3ba2752..fd517d1145e 100644
--- a/test/spec/sizeMapping_spec.js
+++ b/test/spec/sizeMapping_spec.js
@@ -1,123 +1,194 @@
 import { expect } from 'chai';
-import * as sizeMapping from 'src/sizeMapping';
-
-var validAdUnit = {
-  'sizes': [300, 250],
-  'sizeMapping': [
-    {
-      'minWidth': 1024,
-      'sizes': [[300, 250], [728, 90]]
-    },
-    {
-      'minWidth': 480,
-      'sizes': [120, 60]
-    },
-    {
-      'minWidth': 0,
-      'sizes': [20, 20]
-    }
-  ]
-};
-
-var invalidAdUnit = {
-  'sizes': [300, 250],
-  'sizeMapping': {} // wrong type
-};
-
-var invalidAdUnit2 = {
-  'sizes': [300, 250],
-  'sizeMapping': [{
-    foo: 'bar' // bad
-  }]
-};
-
-let mockWindow = {};
-
-function resetMockWindow() {
-  mockWindow = {
-    document: {
-      body: {
-        clientWidth: 1024
-      },
-      documentElement: {
-        clientWidth: 1024
+import { resolveStatus, setSizeConfig } from 'src/sizeMapping';
+
+describe('sizeMapping', () => {
+  var testSizes = [[970, 90], [728, 90], [300, 250], [300, 100], [80, 80]];
+
+  var sizeConfig = [{
+    'mediaQuery': '(min-width: 1200px)',
+    'sizesSupported': [
+      [970, 90],
+      [728, 90],
+      [300, 250]
+    ]
+  }, {
+    'mediaQuery': '(min-width: 768px) and (max-width: 1199px)',
+    'sizesSupported': [
+      [728, 90],
+      [300, 250],
+      [300, 100]
+    ]
+  }, {
+    'mediaQuery': '(min-width: 0px) and (max-width: 767px)',
+    'sizesSupported': []
+  }];
+
+  var sizeConfigWithLabels = [{
+    'mediaQuery': '(min-width: 1200px)',
+    'labels': ['desktop']
+  }, {
+    'mediaQuery': '(min-width: 768px) and (max-width: 1199px)',
+    'sizesSupported': [
+      [728, 90],
+      [300, 250]
+    ],
+    'labels': ['tablet', 'phone']
+  }, {
+    'mediaQuery': '(min-width: 0px) and (max-width: 767px)',
+    'sizesSupported': [
+      [300, 250],
+      [300, 100]
+    ],
+    'labels': ['phone']
+  }];
+
+  let sandbox,
+    matchMediaOverride;
+
+  beforeEach(() => {
+    setSizeConfig(sizeConfig);
+
+    sandbox = sinon.sandbox.create();
+
+    matchMediaOverride = {matches: false};
+
+    sandbox.stub(window, 'matchMedia', (...args) => {
+      if (typeof matchMediaOverride === 'function') {
+        return matchMediaOverride.apply(window, args);
       }
-    },
-    innerWidth: 1024
-  };
-}
-
-describe('sizeMapping', function() {
-  beforeEach(resetMockWindow);
-
-  it('minWidth should be inclusive', function() {
-    mockWindow.innerWidth = 1024;
-    sizeMapping.setWindow(mockWindow);
-    let sizes = sizeMapping.mapSizes(validAdUnit);
-    expect(sizes).to.deep.equal([[300, 250], [728, 90]]);
+      return matchMediaOverride;
+    });
   });
 
-  it('mapSizes 1029 width', function() {
-    mockWindow.innerWidth = 1029;
-    sizeMapping.setWindow(mockWindow);
-    let sizes = sizeMapping.mapSizes(validAdUnit);
-    expect(sizes).to.deep.equal([[300, 250], [728, 90]]);
-    expect(validAdUnit.sizes).to.deep.equal([300, 250]);
-  });
+  afterEach(() => {
+    setSizeConfig([]);
 
-  it('mapSizes 400 width', function() {
-    mockWindow.innerWidth = 400;
-    sizeMapping.setWindow(mockWindow);
-    let sizes = sizeMapping.mapSizes(validAdUnit);
-    expect(sizes).to.deep.equal([20, 20]);
-    expect(validAdUnit.sizes).to.deep.equal([300, 250]);
+    sandbox.restore();
   });
 
-  it('mapSizes - invalid adUnit - should return sizes', function() {
-    mockWindow.innerWidth = 1029;
-    sizeMapping.setWindow(mockWindow);
-    let sizes = sizeMapping.mapSizes(invalidAdUnit);
-    expect(sizes).to.deep.equal([300, 250]);
-    expect(invalidAdUnit.sizes).to.deep.equal([300, 250]);
-
-    mockWindow.innerWidth = 400;
-    sizeMapping.setWindow(mockWindow);
-    sizes = sizeMapping.mapSizes(invalidAdUnit);
-    expect(sizes).to.deep.equal([300, 250]);
-    expect(invalidAdUnit.sizes).to.deep.equal([300, 250]);
-  });
+  describe('when handling sizes', () => {
+    it('when one mediaQuery block matches, it should filter the adUnit.sizes passed in', () => {
+      matchMediaOverride = (str) => str === '(min-width: 1200px)' ? {matches: true} : {matches: false};
 
-  it('mapSizes - should return desktop (largest) sizes if screen width not detected', function() {
-    mockWindow.innerWidth = 0;
-    mockWindow.document.body.clientWidth = 0;
-    mockWindow.document.documentElement.clientWidth = 0;
-    sizeMapping.setWindow(mockWindow);
-    let sizes = sizeMapping.mapSizes(validAdUnit);
-    expect(sizes).to.deep.equal([[300, 250], [728, 90]]);
-    expect(validAdUnit.sizes).to.deep.equal([300, 250]);
-  });
+      let status = resolveStatus(undefined, testSizes, sizeConfig);
 
-  it('mapSizes - should return sizes if sizemapping improperly defined ', function() {
-    mockWindow.innerWidth = 0;
-    mockWindow.document.body.clientWidth = 0;
-    mockWindow.document.documentElement.clientWidth = 0;
-    sizeMapping.setWindow(mockWindow);
-    let sizes = sizeMapping.mapSizes(invalidAdUnit2);
-    expect(sizes).to.deep.equal([300, 250]);
-    expect(validAdUnit.sizes).to.deep.equal([300, 250]);
-  });
+      expect(status).to.deep.equal({
+        active: true,
+        sizes: [[970, 90], [728, 90], [300, 250]]
+      })
+    });
+
+    it('when multiple mediaQuery block matches, it should filter a union of the matched sizesSupported', () => {
+      matchMediaOverride = (str) => [
+        '(min-width: 1200px)',
+        '(min-width: 768px) and (max-width: 1199px)'
+      ].includes(str) ? {matches: true} : {matches: false};
+
+      let status = resolveStatus(undefined, testSizes, sizeConfig);
+      expect(status).to.deep.equal({
+        active: true,
+        sizes: [[970, 90], [728, 90], [300, 250], [300, 100]]
+      })
+    });
+
+    it('if no mediaQueries match, it should allow all sizes specified', () => {
+      matchMediaOverride = () => ({matches: false});
+
+      let status = resolveStatus(undefined, testSizes, sizeConfig);
+      expect(status).to.deep.equal({
+        active: true,
+        sizes: testSizes
+      })
+    });
 
-  it('getScreenWidth', function() {
-    mockWindow.innerWidth = 900;
-    mockWindow.document.body.clientWidth = 900;
-    mockWindow.document.documentElement.clientWidth = 900;
-    expect(sizeMapping.getScreenWidth(mockWindow)).to.equal(900);
+    it('if a mediaQuery matches and has sizesSupported: [], it should filter all sizes', () => {
+      matchMediaOverride = (str) => str === '(min-width: 0px) and (max-width: 767px)' ? {matches: true} : {matches: false};
+
+      let status = resolveStatus(undefined, testSizes, sizeConfig);
+      expect(status).to.deep.equal({
+        active: false,
+        sizes: []
+      })
+    });
+
+    it('if a mediaQuery matches and no sizesSupported specified, it should not effect adUnit.sizes', () => {
+      matchMediaOverride = (str) => str === '(min-width: 1200px)' ? {matches: true} : {matches: false};
+
+      let status = resolveStatus(undefined, testSizes, sizeConfigWithLabels);
+      expect(status).to.deep.equal({
+        active: true,
+        sizes: testSizes
+      })
+    });
   });
 
-  it('getScreenWidth - should return 0 if it cannot deteremine size', function() {
-    mockWindow.innerWidth = null;
-    mockWindow.document.body.clientWidth = null;
-    mockWindow.document.documentElement.clientWidth = null;
-    expect(sizeMapping.getScreenWidth(mockWindow)).to.equal(0);
+  describe('when handling labels', () => {
+    it('should activate/deactivate adUnits/bidders based on sizeConfig.labels', () => {
+      matchMediaOverride = (str) => str === '(min-width: 1200px)' ? {matches: true} : {matches: false};
+
+      let status = resolveStatus({
+        labels: ['desktop']
+      }, testSizes, sizeConfigWithLabels);
+
+      expect(status).to.deep.equal({
+        active: true,
+        sizes: testSizes
+      });
+
+      status = resolveStatus({
+        labels: ['tablet']
+      }, testSizes, sizeConfigWithLabels);
+
+      expect(status).to.deep.equal({
+        active: false,
+        sizes: testSizes
+      });
+    });
+
+    it('should active/deactivate adUnits/bidders based on requestBids labels', () => {
+      let activeLabels = ['us-visitor', 'desktop', 'smart'];
+
+      let status = resolveStatus({
+        labels: ['uk-visitor'],
+        activeLabels
+      }, testSizes, sizeConfigWithLabels);
+
+      expect(status).to.deep.equal({
+        active: false,
+        sizes: testSizes
+      });
+
+      status = resolveStatus({
+        labels: ['us-visitor'],
+        activeLabels
+      }, testSizes, sizeConfigWithLabels);
+
+      expect(status).to.deep.equal({
+        active: true,
+        sizes: testSizes
+      });
+
+      status = resolveStatus({
+        labels: ['us-visitor', 'tablet'],
+        labelAll: true,
+        activeLabels
+      }, testSizes, sizeConfigWithLabels);
+
+      expect(status).to.deep.equal({
+        active: false,
+        sizes: testSizes
+      });
+
+      status = resolveStatus({
+        labels: ['us-visitor', 'desktop'],
+        labelAll: true,
+        activeLabels
+      }, testSizes, sizeConfigWithLabels);
+
+      expect(status).to.deep.equal({
+        active: true,
+        sizes: testSizes
+      });
+    });
   });
 });
diff --git a/test/spec/unit/core/adapterManager_spec.js b/test/spec/unit/core/adapterManager_spec.js
index ac4b2d3b587..8b5f0f714b4 100644
--- a/test/spec/unit/core/adapterManager_spec.js
+++ b/test/spec/unit/core/adapterManager_spec.js
@@ -5,6 +5,7 @@ import CONSTANTS from 'src/constants.json';
 import * as utils from 'src/utils';
 import { config } from 'src/config';
 import { registerBidder } from 'src/adapters/bidderFactory';
+import { setSizeConfig } from 'src/sizeMapping';
 var s2sTesting = require('../../../../modules/s2sTesting');
 
 const CONFIG = {
@@ -303,5 +304,119 @@ describe('adapterManager tests', () => {
         expect(AdapterManager.videoAdapters).to.include(alias);
       });
     });
+
+    describe('makeBidRequests', () => {
+      let adUnits;
+      beforeEach(() => {
+        adUnits = utils.cloneJson(getAdUnits()).map(adUnit => {
+          adUnit.bids = adUnit.bids.filter(bid => ['appnexus', 'rubicon'].includes(bid.bidder));
+          return adUnit;
+        })
+      });
+
+      describe('sizeMapping', () => {
+        beforeEach(() => {
+          sinon.stub(window, 'matchMedia', () => ({matches: true}));
+        });
+
+        afterEach(() => {
+          matchMedia.restore();
+          setSizeConfig([]);
+        });
+
+        it('should not filter bids w/ no labels', () => {
+          let bidRequests = AdapterManager.makeBidRequests(
+            adUnits,
+            Date.now(),
+            utils.getUniqueIdentifierStr(),
+            function callback() {},
+            []
+          );
+
+          expect(bidRequests.length).to.equal(2);
+          let rubiconBidRequests = bidRequests.find(bidRequest => bidRequest.bidderCode === 'rubicon');
+          expect(rubiconBidRequests.bids.length).to.equal(1);
+          expect(rubiconBidRequests.bids[0].sizes).to.deep.equal(adUnits.find(adUnit => adUnit.code === rubiconBidRequests.bids[0].adUnitCode).sizes);
+
+          let appnexusBidRequests = bidRequests.find(bidRequest => bidRequest.bidderCode === 'appnexus');
+          expect(appnexusBidRequests.bids.length).to.equal(2);
+          expect(appnexusBidRequests.bids[0].sizes).to.deep.equal(adUnits.find(adUnit => adUnit.code === appnexusBidRequests.bids[0].adUnitCode).sizes);
+          expect(appnexusBidRequests.bids[1].sizes).to.deep.equal(adUnits.find(adUnit => adUnit.code === appnexusBidRequests.bids[1].adUnitCode).sizes);
+        });
+
+        it('should filter sizes using size config', () => {
+          let validSizes = [
+            [728, 90],
+            [300, 250]
+          ];
+
+          let validSizeMap = validSizes.map(size => size.toString()).reduce((map, size) => {
+            map[size] = true;
+            return map;
+          }, {});
+
+          setSizeConfig([{
+            'mediaQuery': '(min-width: 768px) and (max-width: 1199px)',
+            'sizesSupported': validSizes,
+            'labels': ['tablet', 'phone']
+          }]);
+
+          let bidRequests = AdapterManager.makeBidRequests(
+            adUnits,
+            Date.now(),
+            utils.getUniqueIdentifierStr(),
+            function callback() {},
+            []
+          );
+
+          // only valid sizes as specified in size config should show up in bidRequests
+          bidRequests.forEach(bidRequest => {
+            bidRequest.bids.forEach(bid => {
+              bid.sizes.forEach(size => {
+                expect(validSizeMap[size]).to.equal(true);
+              });
+            });
+          });
+
+          setSizeConfig([{
+            'mediaQuery': '(min-width: 768px) and (max-width: 1199px)',
+            'sizesSupported': [],
+            'labels': ['tablet', 'phone']
+          }]);
+
+          bidRequests = AdapterManager.makeBidRequests(
+            adUnits,
+            Date.now(),
+            utils.getUniqueIdentifierStr(),
+            function callback() {},
+            []
+          );
+
+          // if no valid sizes, all bidders should be filtered out
+          expect(bidRequests.length).to.equal(0);
+        });
+
+        it('should filter adUnits/bidders based on applied labels', () => {
+          adUnits[0].labelAll = ['visitor-uk', 'mobile'];
+          adUnits[1].labelAny = ['visitor-uk', 'desktop'];
+          adUnits[1].bids[0].labelAny = ['mobile'];
+          adUnits[1].bids[1].labelAll = ['desktop'];
+
+          let bidRequests = AdapterManager.makeBidRequests(
+            adUnits,
+            Date.now(),
+            utils.getUniqueIdentifierStr(),
+            function callback() {},
+            ['visitor-uk', 'desktop']
+          );
+
+          // only one adUnit and one bid from that adUnit should make it through the applied labels above
+          expect(bidRequests.length).to.equal(1);
+          expect(bidRequests[0].bidderCode).to.equal('rubicon');
+          expect(bidRequests[0].bids.length).to.equal(1);
+          expect(bidRequests[0].bids[0].adUnitCode).to.equal(adUnits[1].code);
+        });
+      })
+    });
   });
 });
diff --git a/test/spec/unit/pbjs_api_spec.js b/test/spec/unit/pbjs_api_spec.js
index f95b1d12aad..fc82cf4a704 100644
--- a/test/spec/unit/pbjs_api_spec.js
+++ b/test/spec/unit/pbjs_api_spec.js
@@ -898,6 +898,7 @@ describe('Unit: Prebid Module', function () {
         adUnits = [{
           code: 'adUnit-code',
           mediaType: 'video',
+          sizes: [[300, 250], [300, 600]],
           bids: [
             {bidder: 'appnexus', params: {placementId: 'id'}},
             {bidder: 'appnexusAst', params: {placementId: 'id'}}
@@ -933,6 +934,7 @@ describe('Unit: Prebid Module', function () {
         adUnits = [{
           code: 'adUnit-code',
           mediaType: 'video',
+          sizes: [[300, 250], [300, 600]],
           bids: [
             {bidder: 'appnexusAst', params: {placementId: 'id'}}
           ]
@@ -967,6 +969,7 @@ describe('Unit: Prebid Module', function () {
         adUnits = [{
           code: 'adUnit-code',
           mediaType: 'native',
+          sizes: [[300, 250], [300, 600]],
           bids: [
             {bidder: 'appnexus', params: {placementId: 'id'}},
             {bidder: 'appnexusAst', params: {placementId: 'id'}}
@@ -1017,6 +1020,7 @@ describe('Unit: Prebid Module', function () {
         adUnits = [{
           code: 'adUnit-code',
           nativeParams: {type: 'image'},
+          sizes: [[300, 250], [300, 600]],
           bids: [
             {bidder: 'appnexusAst', params: {placementId: 'id'}}
           ]
@@ -1063,6 +1067,7 @@ describe('Unit: Prebid Module', function () {
         let adUnits = [{
           code: 'adUnit-code',
           nativeParams: {type: 'image'},
+          sizes: [[300, 250], [300, 600]],
           bids: [
             {bidder: 'appnexusAst', params: {placementId: 'id'}}
           ]