diff --git a/packages/ember-data/lib/system/relationships/belongs-to.js b/packages/ember-data/lib/system/relationships/belongs-to.js
index 6b2ee6df650..d052b4ee14b 100644
--- a/packages/ember-data/lib/system/relationships/belongs-to.js
+++ b/packages/ember-data/lib/system/relationships/belongs-to.js
@@ -91,18 +91,12 @@ function belongsTo(modelName, options) {
 
   opts = opts || {};
 
-  var shouldWarnAsync = false;
-  if (typeof opts.async === 'undefined') {
-    shouldWarnAsync = true;
-  }
-
   var meta = {
     type: userEnteredModelName,
     isRelationship: true,
     options: opts,
     kind: 'belongsTo',
-    key: null,
-    shouldWarnAsync: shouldWarnAsync
+    key: null
   };
 
   return Ember.computed({
@@ -110,11 +104,6 @@ function belongsTo(modelName, options) {
       Ember.warn('You provided a serialize option on the "' + key + '" property in the "' + this._internalModel.modelName + '" class, this belongs in the serializer. See DS.Serializer and it\'s implementations http://emberjs.com/api/data/classes/DS.Serializer.html', !opts.hasOwnProperty('serialize'));
       Ember.warn('You provided an embedded option on the "' + key + '" property in the "' + this._internalModel.modelName + '" class, this belongs in the serializer. See DS.EmbeddedRecordsMixin http://emberjs.com/api/data/classes/DS.EmbeddedRecordsMixin.html', !opts.hasOwnProperty('embedded'));
 
-      if (meta.shouldWarnAsync) {
-        Ember.deprecate(`In Ember Data 2.0, relationships will be asynchronous by default. You must set \`${key}: DS.belongsTo('${modelName}', { async: false })\` if you wish for a relationship remain synchronous.`);
-        meta.shouldWarnAsycn = false;
-      }
-
       return this._internalModel._relationships.get(key).getRecord();
     },
     set: function(key, value) {
diff --git a/packages/ember-data/lib/system/relationships/has-many.js b/packages/ember-data/lib/system/relationships/has-many.js
index 6acd4e96519..33b50315649 100644
--- a/packages/ember-data/lib/system/relationships/has-many.js
+++ b/packages/ember-data/lib/system/relationships/has-many.js
@@ -121,11 +121,6 @@ function hasMany(type, options) {
 
   options = options || {};
 
-  var shouldWarnAsync = false;
-  if (typeof options.async === 'undefined') {
-    shouldWarnAsync = true;
-  }
-
   if (typeof type === 'string') {
     type = normalizeModelName(type);
   }
@@ -139,16 +134,11 @@ function hasMany(type, options) {
     isRelationship: true,
     options: options,
     kind: 'hasMany',
-    key: null,
-    shouldWarnAsync: shouldWarnAsync
+    key: null
   };
 
   return Ember.computed({
     get: function(key) {
-      if (meta.shouldWarnAsync) {
-        Ember.deprecate(`In Ember Data 2.0, relationships will be asynchronous by default. You must set \`${key}: DS.hasMany('${type}', { async: false })\` if you wish for a relationship remain synchronous.`);
-        meta.shouldWarnAsync = false;
-      }
       var relationship = this._internalModel._relationships.get(key);
       return relationship.getRecords();
     },
diff --git a/packages/ember-data/lib/system/relationships/state/relationship.js b/packages/ember-data/lib/system/relationships/state/relationship.js
index 3a8ccb94feb..cf78b1d2df4 100644
--- a/packages/ember-data/lib/system/relationships/state/relationship.js
+++ b/packages/ember-data/lib/system/relationships/state/relationship.js
@@ -1,13 +1,14 @@
 import OrderedSet from "ember-data/system/ordered-set";
 
 export default function Relationship(store, record, inverseKey, relationshipMeta) {
+  var async = relationshipMeta.options.async;
   this.members = new OrderedSet();
   this.canonicalMembers = new OrderedSet();
   this.store = store;
   this.key = relationshipMeta.key;
   this.inverseKey = inverseKey;
   this.record = record;
-  this.isAsync = relationshipMeta.options.async;
+  this.isAsync = typeof async === 'undefined' ? true : async;
   this.relationshipMeta = relationshipMeta;
   //This probably breaks for polymorphic relationship in complex scenarios, due to
   //multiple possible modelNames
diff --git a/packages/ember-data/tests/integration/filter-test.js b/packages/ember-data/tests/integration/filter-test.js
index acb2fd8243f..eb377062a4f 100644
--- a/packages/ember-data/tests/integration/filter-test.js
+++ b/packages/ember-data/tests/integration/filter-test.js
@@ -43,7 +43,7 @@ module("integration/filter - DS.Model updating", {
         name: 'Scumbag Bryn'
       }
     }];
-    Person = DS.Model.extend({ name: DS.attr('string'), bestFriend: DS.belongsTo('person', { inverse: null }) });
+    Person = DS.Model.extend({ name: DS.attr('string'), bestFriend: DS.belongsTo('person', { inverse: null, async: false }) });
 
     env = setupStore({ person: Person });
     store = env.store;
diff --git a/packages/ember-data/tests/unit/model/relationships/belongs-to-test.js b/packages/ember-data/tests/unit/model/relationships/belongs-to-test.js
index e681e9063b0..f01b3158fec 100644
--- a/packages/ember-data/tests/unit/model/relationships/belongs-to-test.js
+++ b/packages/ember-data/tests/unit/model/relationships/belongs-to-test.js
@@ -312,13 +312,7 @@ test("belongsTo gives a warning when provided with an embedded option", function
   }, /You provided an embedded option on the "hobby" property in the "person" class, this belongs in the serializer. See DS.EmbeddedRecordsMixin/);
 });
 
-module("unit/model/relationships - DS.belongsTo async by default deprecations", {
-  setup: function() {
-    setupStore();
-  }
-});
-
-test("setting DS.belongsTo without async false triggers deprecation", function() {
+test("DS.belongsTo should be async by default", function() {
   var Tag = DS.Model.extend({
     name: DS.attr('string'),
     people: DS.hasMany('person', { async: false })
@@ -332,12 +326,10 @@ test("setting DS.belongsTo without async false triggers deprecation", function()
   var env = setupStore({ tag: Tag, person: Person });
   var store = env.store;
 
-  expectDeprecation(
-    function() {
-      run(function() {
-        store.createRecord('person').get('tag');
-      });
-    },
-    /In Ember Data 2.0, relationships will be asynchronous by default. You must set `tag: DS.belongsTo\('tag', { async: false }\)`/
-  );
+
+  run(function() {
+    var person = store.createRecord('person');
+
+    ok(person.get('tag') instanceof DS.PromiseObject, 'tag should be an async relationship');
+  });
 });
diff --git a/packages/ember-data/tests/unit/model/relationships/has-many-test.js b/packages/ember-data/tests/unit/model/relationships/has-many-test.js
index ae21ccd68f0..b33f4da0648 100644
--- a/packages/ember-data/tests/unit/model/relationships/has-many-test.js
+++ b/packages/ember-data/tests/unit/model/relationships/has-many-test.js
@@ -468,13 +468,7 @@ test("it is possible to add an item to a relationship, remove it, then add it ag
   equal(tags.objectAt(2), tag3);
 });
 
-module("unit/model/relationships - DS.hasMany async by default deprecations", {
-  setup: function() {
-    env = setupStore();
-  }
-});
-
-test("setting DS.hasMany without async false triggers deprecation", function() {
+test("DS.hasMany is async by default", function() {
   var Tag = DS.Model.extend({
     name: DS.attr('string'),
     people: DS.hasMany('person')
@@ -488,12 +482,8 @@ test("setting DS.hasMany without async false triggers deprecation", function() {
   var env = setupStore({ tag: Tag, person: Person });
   var store = env.store;
 
-  expectDeprecation(
-    function() {
-      run(function() {
-        store.createRecord('tag').get('people');
-      });
-    },
-    /In Ember Data 2.0, relationships will be asynchronous by default. You must set `people: DS.hasMany\('person', { async: false }\)/
-  );
+  run(function() {
+    var tag = store.createRecord('tag');
+    ok(tag.get('people') instanceof DS.PromiseArray, 'people should be an async relationship');
+  });
 });