diff --git a/lib/objects.js b/lib/objects.js
index 135005b6..e22a0a45 100644
--- a/lib/objects.js
+++ b/lib/objects.js
@@ -32,6 +32,13 @@ function create(realmId, info) {
         });
     });
 
+    if (constructor) {
+        let result = constructor.call(object);
+        if (result != null && result != object) {
+            throw new Error('Realm object constructor must not return another value');
+        }
+    }
+
     return object;
 }
 
diff --git a/lib/realm.js b/lib/realm.js
index 608e0b08..ae4f82a1 100644
--- a/lib/realm.js
+++ b/lib/realm.js
@@ -20,16 +20,27 @@ rpc.registerTypeConverter(objectTypes.RESULTS, results.create);
 
 class Realm {
     constructor(config) {
-        let schema = typeof config == 'object' && config.schema;
+        let schemas = typeof config == 'object' && config.schema;
         let constructors = {};
 
-        for (let i = 0, len = schema ? schema.length : 0; i < len; i++) {
-            let item = schema[i];
-            let proto = item.prototype;
+        for (let i = 0, len = schemas ? schemas.length : 0; i < len; i++) {
+            let item = schemas[i];
 
-            if (proto && proto.schema) {
-                schema.splice(i, 1, proto.schema);
-                constructors[proto.schema.name] = item;
+            if (typeof item == 'function') {
+                let schema = item.schema;
+                if (!schema || typeof schema != 'object') {
+                    throw new Error("Realm object constructor must have 'schema' property");
+                }
+
+                let {name, properties} = schema;
+                if (!name || typeof name != 'string') {
+                    throw new Error("Realm object schema must have 'name' property");
+                } else if (!properties || typeof properties != 'object') {
+                    throw new Error("Realm object schema must have 'properties' property"); 
+                }
+
+                schemas.splice(i, 1, schema);
+                constructors[name] = item;
             }
         }
 
diff --git a/src/js_object.cpp b/src/js_object.cpp
index 19e1ce7b..2dc8f0f8 100644
--- a/src/js_object.cpp
+++ b/src/js_object.cpp
@@ -58,8 +58,24 @@ JSClassRef RJSObjectClass() {
 }
 
 JSObjectRef RJSObjectCreate(JSContextRef ctx, Object object) {
-    JSValueRef prototype = RJSPrototypes(object.realm().get())[object.get_object_schema().name];
+    static JSStringRef prototypeString = JSStringCreateWithUTF8CString("prototype");
+
+    JSObjectRef constructor = RJSConstructors(object.realm().get())[object.get_object_schema().name];
+    JSObjectRef prototype = constructor ? RJSValidatedObjectProperty(ctx, constructor, prototypeString) : NULL;
     JSObjectRef jsObject = RJSWrapObject(ctx, RJSObjectClass(), new Object(object), prototype);
+
+    if (constructor) {
+        JSValueRef exception = NULL;
+        JSValueRef result = JSObjectCallAsFunction(ctx, constructor, jsObject, 0, NULL, &exception);
+
+        if (exception) {
+            throw RJSException(ctx, exception);
+        }
+        else if (result != jsObject && !JSValueIsNull(ctx, result) && !JSValueIsUndefined(ctx, result)) {
+            throw std::runtime_error("Realm object constructor must not return another value");
+        }
+    }
+
     return jsObject;
 }
 
diff --git a/src/js_realm.cpp b/src/js_realm.cpp
index c2196ce5..8fc6ce5c 100644
--- a/src/js_realm.cpp
+++ b/src/js_realm.cpp
@@ -39,8 +39,8 @@ public:
     ~RJSRealmDelegate() {
         remove_all_notifications();
 
-        for (auto prototype : m_prototypes) {
-            JSValueUnprotect(m_context, prototype.second);
+        for (auto constructor : m_constructors) {
+            JSValueUnprotect(m_context, constructor.second);
         }
         for (auto objectDefaults : m_defaults) {
             for (auto value : objectDefaults.second) {
@@ -70,7 +70,7 @@ public:
     }
 
     std::map<std::string, ObjectDefaults> m_defaults;
-    std::map<std::string, JSValueRef> m_prototypes;
+    std::map<std::string, JSObjectRef> m_constructors;
 
   private:
     std::set<JSObjectRef> m_notifications;
@@ -101,8 +101,8 @@ std::map<std::string, ObjectDefaults> &RJSDefaults(Realm *realm) {
     return static_cast<RJSRealmDelegate *>(realm->m_binding_context.get())->m_defaults;
 }
 
-std::map<std::string, JSValueRef> &RJSPrototypes(Realm *realm) {
-    return static_cast<RJSRealmDelegate *>(realm->m_binding_context.get())->m_prototypes;
+std::map<std::string, JSObjectRef> &RJSConstructors(Realm *realm) {
+    return static_cast<RJSRealmDelegate *>(realm->m_binding_context.get())->m_constructors;
 }
 
 // static std::string s_defaultPath = realm::default_realm_file_directory() + "/default.realm";
@@ -137,7 +137,7 @@ JSObjectRef RealmConstructor(JSContextRef ctx, JSObjectRef constructor, size_t a
     try {
         Realm::Config config;
         std::map<std::string, realm::ObjectDefaults> defaults;
-        std::map<std::string, JSValueRef> prototypes;
+        std::map<std::string, JSObjectRef> constructors;
         switch (argumentCount) {
             case 0:
                 config.path = RJSDefaultPath();
@@ -163,7 +163,7 @@ JSObjectRef RealmConstructor(JSContextRef ctx, JSObjectRef constructor, size_t a
                     static JSStringRef schemaString = JSStringCreateWithUTF8CString("schema");
                     JSValueRef schemaValue = RJSValidatedPropertyValue(ctx, object, schemaString);
                     if (!JSValueIsUndefined(ctx, schemaValue)) {
-                        config.schema.reset(new Schema(RJSParseSchema(ctx, RJSValidatedValueToObject(ctx, schemaValue), defaults, prototypes)));
+                        config.schema.reset(new Schema(RJSParseSchema(ctx, RJSValidatedValueToObject(ctx, schemaValue), defaults, constructors)));
                     }
 
                     static JSStringRef schemaVersionString = JSStringCreateWithUTF8CString("schemaVersion");
@@ -187,7 +187,7 @@ JSObjectRef RealmConstructor(JSContextRef ctx, JSObjectRef constructor, size_t a
             realm->m_binding_context.reset(new RJSRealmDelegate(realm, JSContextGetGlobalContext(ctx)));
         }
         RJSDefaults(realm.get()) = defaults;
-        RJSPrototypes(realm.get()) = prototypes;
+        RJSConstructors(realm.get()) = constructors;
         return RJSWrapObject<SharedRealm *>(ctx, RJSRealmClass(), new SharedRealm(realm));
     }
     catch (std::exception &ex) {
diff --git a/src/js_realm.hpp b/src/js_realm.hpp
index fa2b4fdd..d7e248b5 100644
--- a/src/js_realm.hpp
+++ b/src/js_realm.hpp
@@ -19,4 +19,4 @@ std::string RJSDefaultPath();
 void RJSSetDefaultPath(std::string path);
 
 std::map<std::string, realm::ObjectDefaults> &RJSDefaults(realm::Realm *realm);
-std::map<std::string, JSValueRef> &RJSPrototypes(realm::Realm *realm);
+std::map<std::string, JSObjectRef> &RJSConstructors(realm::Realm *realm);
diff --git a/src/js_schema.cpp b/src/js_schema.cpp
index 20e02f32..6cc67226 100644
--- a/src/js_schema.cpp
+++ b/src/js_schema.cpp
@@ -114,19 +114,17 @@ static inline Property RJSParseProperty(JSContextRef ctx, JSValueRef propertyAtt
     return prop;
 }
 
-static inline ObjectSchema RJSParseObjectSchema(JSContextRef ctx, JSObjectRef objectSchemaObject, std::map<std::string, realm::ObjectDefaults> &defaults, std::map<std::string, JSValueRef> &prototypes) {
+static inline ObjectSchema RJSParseObjectSchema(JSContextRef ctx, JSObjectRef objectSchemaObject, std::map<std::string, realm::ObjectDefaults> &defaults, std::map<std::string, JSObjectRef> &constructors) {
     static JSStringRef nameString = JSStringCreateWithUTF8CString("name");
     static JSStringRef primaryString = JSStringCreateWithUTF8CString("primaryKey");
-    static JSStringRef prototypeString = JSStringCreateWithUTF8CString("prototype");
     static JSStringRef propertiesString = JSStringCreateWithUTF8CString("properties");
     static JSStringRef schemaString = JSStringCreateWithUTF8CString("schema");
 
-    JSObjectRef prototypeObject = NULL;
-    JSValueRef prototypeValue = RJSValidatedPropertyValue(ctx, objectSchemaObject, prototypeString);
+    JSObjectRef objectConstructor = NULL;
 
-    if (!JSValueIsUndefined(ctx, prototypeValue)) {
-        prototypeObject = RJSValidatedValueToObject(ctx, prototypeValue);
-        objectSchemaObject = RJSValidatedObjectProperty(ctx, prototypeObject, schemaString, "Realm object prototype must have a 'schema' property.");
+    if (JSObjectIsFunction(ctx, objectSchemaObject) || JSObjectIsConstructor(ctx, objectSchemaObject)) {
+        objectConstructor = objectSchemaObject;
+        objectSchemaObject = RJSValidatedObjectProperty(ctx, objectConstructor, schemaString, "Realm object constructor must have a 'schema' property.");
     }
     else {
         JSValueRef subSchemaValue = RJSValidatedPropertyValue(ctx, objectSchemaObject, schemaString);
@@ -170,9 +168,9 @@ static inline ObjectSchema RJSParseObjectSchema(JSContextRef ctx, JSObjectRef ob
     }
 
     // Store prototype so that objects of this type will have their prototype set to this prototype object.
-    if (prototypeObject) {
-        JSValueProtect(ctx, prototypeObject);
-        prototypes[objectSchema.name] = std::move(prototypeObject);
+    if (objectConstructor) {
+        JSValueProtect(ctx, objectConstructor);
+        constructors[objectSchema.name] = std::move(objectConstructor);
     }
 
     defaults.emplace(objectSchema.name, std::move(objectDefaults));
@@ -180,12 +178,12 @@ static inline ObjectSchema RJSParseObjectSchema(JSContextRef ctx, JSObjectRef ob
     return objectSchema;
 }
 
-realm::Schema RJSParseSchema(JSContextRef ctx, JSObjectRef jsonObject, std::map<std::string, realm::ObjectDefaults> &defaults, std::map<std::string, JSValueRef> &prototypes) {
+realm::Schema RJSParseSchema(JSContextRef ctx, JSObjectRef jsonObject, std::map<std::string, realm::ObjectDefaults> &defaults, std::map<std::string, JSObjectRef> &constructors) {
     std::vector<ObjectSchema> schema;
     size_t length = RJSValidatedListLength(ctx, jsonObject);
     for (unsigned int i = 0; i < length; i++) {
         JSObjectRef jsonObjectSchema = RJSValidatedObjectAtIndex(ctx, jsonObject, i);
-        ObjectSchema objectSchema = RJSParseObjectSchema(ctx, jsonObjectSchema, defaults, prototypes);
+        ObjectSchema objectSchema = RJSParseObjectSchema(ctx, jsonObjectSchema, defaults, constructors);
         schema.emplace_back(std::move(objectSchema));
      }
 
diff --git a/src/js_schema.hpp b/src/js_schema.hpp
index 4564fcf4..6de643f6 100644
--- a/src/js_schema.hpp
+++ b/src/js_schema.hpp
@@ -15,4 +15,4 @@ namespace realm {
 JSClassRef RJSSchemaClass();
 JSObjectRef RJSSchemaCreate(JSContextRef ctx, realm::Schema *schema);
 
-realm::Schema RJSParseSchema(JSContextRef ctx, JSObjectRef jsonObject, std::map<std::string, realm::ObjectDefaults> &defaults, std::map<std::string, JSValueRef> &prototypes);
+realm::Schema RJSParseSchema(JSContextRef ctx, JSObjectRef jsonObject, std::map<std::string, realm::ObjectDefaults> &defaults, std::map<std::string, JSObjectRef> &constructors);
diff --git a/tests/lib/realm-tests.js b/tests/lib/realm-tests.js
index c19736e2..4c42e969 100644
--- a/tests/lib/realm-tests.js
+++ b/tests/lib/realm-tests.js
@@ -261,6 +261,53 @@ module.exports = BaseTest.extend({
         });
     },
 
+    testRealmCreateWithConstructor: function() {
+        var customCreated = 0;
+
+        function CustomObject() {
+            customCreated++;
+            this.intCol *= 100;
+        }
+        CustomObject.schema = {
+            name: 'CustomObject',
+            properties: {
+                intCol: 'int'
+            }
+        }
+
+        function InvalidObject() {
+            return {};
+        }
+        TestCase.assertThrows(function() {
+            new Realm({schema: [InvalidObject]});
+        });
+
+        InvalidObject.schema = {
+            name: 'InvalidObject',
+            properties: {
+                intCol: 'int'
+            }
+        }
+
+        var realm = new Realm({schema: [CustomObject, InvalidObject]});
+
+        realm.write(function() {
+            var object = realm.create('CustomObject', {intCol: 1});
+            TestCase.assertTrue(object instanceof CustomObject);
+            TestCase.assertTrue(Object.getPrototypeOf(object) == CustomObject.prototype);
+            TestCase.assertEqual(customCreated, 1);
+
+            // Should have been multiplied by 100 in the constructor.
+            TestCase.assertEqual(object.intCol, 100);
+        });
+
+        TestCase.assertThrows(function() {
+            realm.write(function() {
+                realm.create('InvalidObject', {intCol: 1});
+            });
+        });
+    },
+
     testRealmDelete: function() {
         var realm = new Realm({schema: [schemas.TestObject]});
 
diff --git a/tests/lib/schemas.js b/tests/lib/schemas.js
index c3b414af..a7c81940 100644
--- a/tests/lib/schemas.js
+++ b/tests/lib/schemas.js
@@ -14,7 +14,7 @@ exports.TestObject = {
 };
 
 function PersonObject() {}
-PersonObject.prototype.schema = {
+PersonObject.schema = {
     name: 'PersonObject',
     properties: {
         name:    Realm.Types.STRING,