diff --git a/CHANGELOG.md b/CHANGELOG.md
index 45d3012b..8b79948d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,7 +4,7 @@ vNext Release notes (TBD)
 * None
 
 ### Enhancements
-* None.
+* Added `indexOf()` method on `Realm.Results` and `Realm.List` that returns the index of the object in the collection.
 
 ### Bug fixes
 * Fix opening synced realms with a logged-in admin user. 
diff --git a/docs/collection.js b/docs/collection.js
index d81fa882..5cb8852e 100644
--- a/docs/collection.js
+++ b/docs/collection.js
@@ -164,6 +164,16 @@ class Collection {
      */
     findIndex(callback, thisArg) {}
 
+   /**
+    Finds the index of the given object in the collection.
+    * @param {Realm.Object} [object] - The object to search for in the collection.
+    * @throws {Error} If the argument does not belong to the realm.
+    * @returns {number} representing the index where the object was found, or `-1`
+    *   if not in collection.
+    * @since 1.8.2
+    */
+   indexOf(object) {}
+
     /**
      * @see {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/forEach Array.prototype.forEach}
      * @param {function} callback - Function to execute on each object in the collection.
diff --git a/lib/browser/lists.js b/lib/browser/lists.js
index df4e63c7..3b67de52 100644
--- a/lib/browser/lists.js
+++ b/lib/browser/lists.js
@@ -30,7 +30,8 @@ createMethods(List.prototype, objectTypes.LIST, [
     'filtered',
     'sorted',
     'snapshot',
-    'isValid',    
+    'isValid',
+    'indexOf',
     'addListener',
     'removeListener',
     'removeAllListeners',
diff --git a/lib/browser/results.js b/lib/browser/results.js
index 6dd4e6b0..72abba67 100644
--- a/lib/browser/results.js
+++ b/lib/browser/results.js
@@ -30,6 +30,7 @@ createMethods(Results.prototype, objectTypes.RESULTS, [
     'sorted',
     'snapshot',
     'isValid',
+    'indexOf',
     'addListener',
     'removeListener',
     'removeAllListeners',
diff --git a/lib/collection-methods.js b/lib/collection-methods.js
index 24f5b791..e2632d4d 100644
--- a/lib/collection-methods.js
+++ b/lib/collection-methods.js
@@ -36,7 +36,6 @@ Object.defineProperty(iteratorPrototype, Symbol.iterator, {
     'concat',
     'join',
     'slice',
-    'indexOf',
     'lastIndexOf',
     'every',
     'some',
diff --git a/src/js_list.hpp b/src/js_list.hpp
index 92189718..6b201cf4 100644
--- a/src/js_list.hpp
+++ b/src/js_list.hpp
@@ -72,7 +72,8 @@ struct ListClass : ClassDefinition<T, realm::js::List<T>, CollectionClass<T>> {
     static void filtered(ContextType, FunctionType, ObjectType, size_t, const ValueType[], ReturnValue &);
     static void sorted(ContextType, FunctionType, ObjectType, size_t, const ValueType[], ReturnValue &);
     static void is_valid(ContextType, FunctionType, ObjectType, size_t, const ValueType[], ReturnValue &);
-    
+    static void index_of(ContextType, FunctionType, ObjectType, size_t, const ValueType[], ReturnValue &);
+
     // observable
     static void add_listener(ContextType, FunctionType, ObjectType, size_t, const ValueType[], ReturnValue &);
     static void remove_listener(ContextType, FunctionType, ObjectType, size_t, const ValueType[], ReturnValue &);
@@ -90,6 +91,7 @@ struct ListClass : ClassDefinition<T, realm::js::List<T>, CollectionClass<T>> {
         {"filtered", wrap<filtered>},
         {"sorted", wrap<sorted>},
         {"isValid", wrap<is_valid>},
+        {"indexOf", wrap<index_of>},
         {"addListener", wrap<add_listener>},
         {"removeListener", wrap<remove_listener>},
         {"removeAllListeners", wrap<remove_all_listeners>},
@@ -256,7 +258,33 @@ template<typename T>
 void ListClass<T>::is_valid(ContextType ctx, FunctionType, ObjectType this_object, size_t argc, const ValueType arguments[], ReturnValue &return_value) {
     return_value.set(get_internal<T, ListClass<T>>(this_object)->is_valid());
 }
-    
+
+template<typename T>
+void ListClass<T>::index_of(ContextType ctx, FunctionType, ObjectType this_object, size_t argc, const ValueType arguments[], ReturnValue &return_value) {
+    validate_argument_count(argc, 1);
+
+    ObjectType arg = Value::validated_to_object(ctx, arguments[0]);
+    if (Object::template is_instance<RealmObjectClass<T>>(ctx, arg)) {
+        auto object = get_internal<T, RealmObjectClass<T>>(arg);
+        if (!object->is_valid()) {
+            throw std::runtime_error("Object is invalid. Either it has been previously deleted or the Realm it belongs to has been closed.");
+        }
+
+        auto list = get_internal<T, ListClass<T>>(this_object);
+        size_t ndx = list->find(object->row());
+
+        if (ndx == realm::not_found) {
+            return_value.set(-1);
+        }
+        else {
+            return_value.set((uint32_t)ndx);
+        }
+    }
+    else {
+        return_value.set(-1);
+    }
+}
+
 template<typename T>
 void ListClass<T>::add_listener(ContextType ctx, FunctionType, ObjectType this_object, size_t argc, const ValueType arguments[], ReturnValue &return_value) {
     validate_argument_count(argc, 1);
diff --git a/src/js_results.hpp b/src/js_results.hpp
index 0b1158d9..894a6c81 100644
--- a/src/js_results.hpp
+++ b/src/js_results.hpp
@@ -74,6 +74,8 @@ struct ResultsClass : ClassDefinition<T, realm::js::Results<T>, CollectionClass<
     static void sorted(ContextType, FunctionType, ObjectType, size_t, const ValueType[], ReturnValue &);
     static void is_valid(ContextType, FunctionType, ObjectType, size_t, const ValueType[], ReturnValue &);
 
+    static void index_of(ContextType, FunctionType, ObjectType, size_t, const ValueType[], ReturnValue &);
+    
     // observable
     static void add_listener(ContextType, FunctionType, ObjectType, size_t, const ValueType[], ReturnValue &);
     static void remove_listener(ContextType, FunctionType, ObjectType, size_t, const ValueType[], ReturnValue &);
@@ -89,6 +91,7 @@ struct ResultsClass : ClassDefinition<T, realm::js::Results<T>, CollectionClass<
         {"addListener", wrap<add_listener>},
         {"removeListener", wrap<remove_listener>},
         {"removeAllListeners", wrap<remove_all_listeners>},
+        {"indexOf", wrap<index_of>},
     };
     
     PropertyMap<T> const properties = {
@@ -238,6 +241,38 @@ void ResultsClass<T>::is_valid(ContextType ctx, FunctionType, ObjectType this_ob
     return_value.set(get_internal<T, ResultsClass<T>>(this_object)->is_valid());
 }
     
+template<typename T>
+void ResultsClass<T>::index_of(ContextType ctx, FunctionType, ObjectType this_object, size_t argc, const ValueType arguments[], ReturnValue &return_value) {
+    validate_argument_count(argc, 1);
+    
+    ObjectType arg = Value::validated_to_object(ctx, arguments[0]);
+    if (Object::template is_instance<RealmObjectClass<T>>(ctx, arg)) {
+        auto object = get_internal<T, RealmObjectClass<T>>(arg);
+        if (!object->is_valid()) {
+            throw std::runtime_error("Object is invalid. Either it has been previously deleted or the Realm it belongs to has been closed.");
+        }
+        
+        size_t ndx;
+        try {
+            auto results = get_internal<T, ResultsClass<T>>(this_object);
+            ndx = results->index_of(object->row());
+        }
+        catch (realm::Results::IncorrectTableException &) {
+            throw std::runtime_error("Object type does not match the type contained in result");
+        }
+        
+        if (ndx == realm::not_found) {
+            return_value.set(-1);
+        }
+        else {
+            return_value.set((uint32_t)ndx);
+        }
+    }
+    else {
+        return_value.set(-1);
+    }
+}
+    
 template<typename T>
 void ResultsClass<T>::add_listener(ContextType ctx, FunctionType, ObjectType this_object, size_t argc, const ValueType arguments[], ReturnValue &return_value) {
     validate_argument_count(argc, 1);
diff --git a/tests/js/list-tests.js b/tests/js/list-tests.js
index 9389add2..8fc71910 100644
--- a/tests/js/list-tests.js
+++ b/tests/js/list-tests.js
@@ -583,6 +583,7 @@ module.exports = {
 
             var index = list.findIndex(function(p) {return p.name == 'Tim'});
             TestCase.assertEqual(index, 1);
+            TestCase.assertEqual(list.indexOf(list[index]), index);
 
             TestCase.assertEqual(list.reduce(function(n, p) {return n + p.age}, 0), 33);
             TestCase.assertEqual(list.reduceRight(function(n, p) {return n + p.age}, 0), 33);
diff --git a/tests/js/results-tests.js b/tests/js/results-tests.js
index 40d332d8..3e974910 100644
--- a/tests/js/results-tests.js
+++ b/tests/js/results-tests.js
@@ -383,6 +383,42 @@ module.exports = {
             TestCase.assertEqual(snapshot.length, 0);
         });
     },
+    
+    testResultsFindIndexOfObject: function() {
+        var realm = new Realm({schema: [schemas.TestObject]});
+        
+        var object1, object2, object3;
+        realm.write(function() {
+            object1 = realm.create('TestObject', {doubleCol: 1});
+            object2 = realm.create('TestObject', {doubleCol: 2});
+            object3 = realm.create('TestObject', {doubleCol: 2});
+        });
+        
+        // Search in base table
+        const objects = realm.objects('TestObject');
+        TestCase.assertEqual(objects.indexOf(object1), 0);
+        TestCase.assertEqual(objects.indexOf(object2), 1);
+        TestCase.assertEqual(objects.indexOf(object3), 2);
+        
+        // Search in filtered query
+        const results = objects.filtered("doubleCol == 2");
+        TestCase.assertEqual(results.indexOf(object1), -1);
+        TestCase.assertEqual(results.indexOf(object2), 0);
+        TestCase.assertEqual(results.indexOf(object3), 1);
+
+        const nonRealmObject = {test: "this is an object"};
+        TestCase.assertEqual(objects.indexOf(nonRealmObject), -1);
+        
+        // Searching for object from the wrong realm
+        var realm2 = new Realm({path: '2.realm', schema: realm.schema});
+        var object4;
+        realm2.write(function() {
+            object4 = realm2.create('TestObject', {doubleCol: 1});
+        });
+        TestCase.assertThrows(function() {
+            objects.indexOf(object4);
+        });
+    },
 
     testAddListener: function() {
         return new Promise((resolve, _reject) => {
@@ -408,4 +444,6 @@ module.exports = {
             });
         })
     }
+    
+    
 };