diff --git a/src/common.js b/src/common.js
index e7f2dd8..380f40c 100644
--- a/src/common.js
+++ b/src/common.js
@@ -9,6 +9,7 @@ function Common() {
 
 Common.prototype.eventMapping = {};
 Common.prototype.customVariablesMappings = {};
+Common.prototype.customFieldMappings = {};
 Common.prototype.settings = {};
 Common.prototype.setCustomVariables = function(event, gtagProperties) {
     for (var attribute in event.EventAttributes) {
@@ -18,6 +19,20 @@ Common.prototype.setCustomVariables = function(event, gtagProperties) {
         }
     }
 };
+Common.prototype.setCustomFields = function(event, gtagProperties) {
+    var dc_custom_params = {};
+    var hasMappings = false;
+    for (var attribute in event.EventAttributes) {
+        if (this.customFieldMappings[attribute]) {
+            dc_custom_params[this.customFieldMappings[attribute]] =
+                event.EventAttributes[attribute];
+            hasMappings = true;
+        }
+    }
+    if (hasMappings) {
+        gtagProperties["dc_custom_params"] = dc_custom_params;
+    }
+};
 Common.prototype.setSendTo = function(mapping, customFlags, gtagProperties) {
     var tags = mapping.value.split(';');
     var groupTag = tags[0];
diff --git a/src/event-handler.js b/src/event-handler.js
index cf7058e..4c9249a 100644
--- a/src/event-handler.js
+++ b/src/event-handler.js
@@ -18,6 +18,7 @@ EventHandler.prototype.logEvent = function (event) {
 
     var gtagProperties = {};
     this.common.setCustomVariables(event, gtagProperties);
+    this.common.setCustomFields(event, gtagProperties);
     var eventMapping = this.common.getEventMapping(event);
 
     if (!eventMapping) {
diff --git a/src/initialization.js b/src/initialization.js
index 2f322b1..b4df68b 100644
--- a/src/initialization.js
+++ b/src/initialization.js
@@ -79,6 +79,12 @@ function initializeGoogleDFP(common, settings, isInitialized) {
         a[b.map] = b.value;
         return a;
     }, {});
+    common.customFieldMappings = parseSettingsString(
+        settings.customParams
+    ).reduce(function (a, b) {
+        a[b.map] = b.value;
+        return a;
+    }, {});
     common.sendGtag('js', new Date(), true);
     common.sendGtag('allow_custom_scripts', true, true);
     common.sendGtag('config', settings.advertiserId, true);
diff --git a/test/tests.js b/test/tests.js
index 1d4a510..677ecae 100644
--- a/test/tests.js
+++ b/test/tests.js
@@ -161,6 +161,7 @@ describe('DoubleClick', function () {
         var sdkSettings = {
             advertiserId: '123456',
             customVariables: '[{"jsmap":null,"map":"Total Amount","maptype":"EventAttributeClass.Name","value":"u1"},{"jsmap":null,"map":"color","maptype":"EventAttributeClass.Name","value":"u2"}]',
+            customParams: '[{"jsmap":null,"map":"product_id","maptype":"EventAttributeClass.Name","value":"dc_product_id"},{"jsmap":null,"map":"category","maptype":"EventAttributeClass.Name","value":"dc_category"}]',
             eventMapping: '[{"jsmap":"-1978027768","map":"-1711833867978608722","maptype":"EventClass.Id","value":"group tag2;activity tag2"},{"jsmap":"-1107730368","map":"-3234618101041058100","maptype":"EventClass.Id","value":"group tag3;activity tag3"},{"jsmap":"-1592184962","map":"-4153695833896571372","maptype":"EventClassDetails.Id","value":"group tag4;activity tag4"}]'
         };
         // You may require userAttributes or userIdentities to be passed into initialization
@@ -504,6 +505,34 @@ describe('DoubleClick', function () {
         done();
     });
 
+    it('should log event with custom field mappings', function(done) {
+        window.dataLayer = [];
+        mParticle.forwarder.process({
+            EventDataType: MessageTypes.PageEvent,
+            EventCategory: mParticle.EventType.Unknown,
+            EventName: 'Test Event',
+            EventAttributes: {
+                'product_id': '12345',
+                'category': 'electronics',
+                'Total Amount': 123,
+                'color': 'blue'
+            },
+            CustomFlags: {
+                'DoubleClick.Counter': 'standard'
+            }
+        });
+        window.dataLayer[0][0].should.equal('event');
+        window.dataLayer[0][1].should.equal('conversion');
+        window.dataLayer[0][2].should.have.property('u1', 123);
+        window.dataLayer[0][2].should.have.property('u2', 'blue');
+        window.dataLayer[0][2].should.have.property('dc_custom_params');
+        window.dataLayer[0][2].dc_custom_params.should.have.property('dc_product_id', '12345');
+        window.dataLayer[0][2].dc_custom_params.should.have.property('dc_category', 'electronics');
+        window.dataLayer[0][2].should.have.property('send_to', 'DC-123456/group tag2/activity tag2+standard');
+
+        done();
+    });
+
     describe('Consent State', function () {
         var consentMap = [
             {
@@ -544,6 +573,7 @@ describe('DoubleClick', function () {
                         '[{"jsmap":null,"map":"Some_consent","maptype":"ConsentPurposes","value":"ad_user_data"},{"jsmap":null,"map":"Storage_consent","maptype":"ConsentPurposes","value":"analytics_storage"},{"jsmap":null,"map":"Other_test_consent","maptype":"ConsentPurposes","value":"ad_storage"},{"jsmap":null,"map":"Test_consent","maptype":"ConsentPurposes","value":"ad_personalization"}]',
                     eventMapping: '[]',
                     customVariables: '[]',
+                    customParams: '[]',
                 },
                 reportService.cb,
                 true
@@ -579,6 +609,7 @@ describe('DoubleClick', function () {
                     defaultAnalyticsStorageConsentWeb: 'Granted',
                     eventMapping: '[]',
                     customVariables: '[]',
+                    customParams: '[]',
                 },
                 reportService.cb,
                 true
@@ -631,6 +662,7 @@ describe('DoubleClick', function () {
                     defaultAnalyticsStorageConsentWeb: 'Unspecified',
                     eventMapping: '[]',
                     customVariables: '[]',
+                    customParams: '[]',
                 },
                 reportService.cb,
                 true
@@ -663,6 +695,7 @@ describe('DoubleClick', function () {
                     consentMappingWeb: JSON.stringify(consentMap),
                     eventMapping: '[]',
                     customVariables: '[]',
+                    customParams: '[]',
                 },
                 reportService.cb,
                 true
@@ -829,6 +862,7 @@ describe('DoubleClick', function () {
                     defaultAnalyticsStorageConsentWeb: 'Granted',
                     eventMapping: '[]',
                     customVariables: '[]',
+                    customParams: '[]',
                 },
                 reportService.cb,
                 true
@@ -1010,6 +1044,7 @@ describe('DoubleClick', function () {
                     consentMappingWeb: JSON.stringify(consentMap),
                     eventMapping: '[]',
                     customVariables: '[]',
+                    customParams: '[]',
                 },
                 reportService.cb,
                 true
@@ -1074,6 +1109,7 @@ describe('DoubleClick', function () {
                     enableGtag: 'True',
                     eventMapping: '[]',
                     customVariables: '[]',
+                    customParams: '[]',
                 },
                 reportService.cb,
                 true
@@ -1153,6 +1189,7 @@ describe('DoubleClick', function () {
                     defaultAnalyticsStorageConsentWeb: 'Denied',
                     eventMapping: '[]',
                     customVariables: '[]',
+                    customParams: '[]',
                 },
                 reportService.cb,
                 true