diff --git a/src/Collection.php b/src/Collection.php
index 5b459d8..c5dcc07 100644
--- a/src/Collection.php
+++ b/src/Collection.php
@@ -4,12 +4,13 @@
 use BapCat\Collection\Interfaces\WritableCollection as WritableCollectionInterface;
 use BapCat\Collection\Traits\CollectionTrait;
 
+use Countable;
 use IteratorAggregate;
 
 /**
  * A readable, writable, iterable collection
  */
-class Collection implements CollectionInterface, WritableCollectionInterface, IteratorAggregate {
+class Collection implements Countable, CollectionInterface, WritableCollectionInterface, IteratorAggregate {
   use CollectionTrait;
   
   public function __construct(array $initial = []) {
diff --git a/src/Interfaces/Collection.php b/src/Interfaces/Collection.php
index 03a8916..53d9ce1 100644
--- a/src/Interfaces/Collection.php
+++ b/src/Interfaces/Collection.php
@@ -84,6 +84,13 @@ public function values();
    * @returns int The size of the collection
    */
   public function size();
+
+  /**
+   * Get the size of the collection
+   * 
+   * @returns int The size of the collection
+   */
+  public function count();
   
   /**
    * Merges two collections together.  If the arrays contain `string` keys, the values
diff --git a/src/ReadOnlyCollection.php b/src/ReadOnlyCollection.php
index d0c1fd8..fd434f4 100644
--- a/src/ReadOnlyCollection.php
+++ b/src/ReadOnlyCollection.php
@@ -4,12 +4,13 @@
 use BapCat\Collection\Traits\ReadableCollectionTrait;
 use BapCat\Collection\Traits\IterableCollectionTrait;
 
+use Countable;
 use IteratorAggregate;
 
 /**
  * A readable, writable, iterable collection
  */
-class ReadOnlyCollection implements CollectionInterface, IteratorAggregate {
+class ReadOnlyCollection implements Countable, CollectionInterface, IteratorAggregate {
   use ReadableCollectionTrait;
   use IterableCollectionTrait;
   
diff --git a/src/Traits/ReadableCollectionTrait.php b/src/Traits/ReadableCollectionTrait.php
index 15d520d..09afa16 100644
--- a/src/Traits/ReadableCollectionTrait.php
+++ b/src/Traits/ReadableCollectionTrait.php
@@ -146,6 +146,18 @@ public function values() {
   public function size() {
     return count($this->collection);
   }
+
+  /**
+   * Get the number of elements in the collection; Required for Countable interface
+   * 
+   * @see Countable
+   * @see self::size()
+   * 
+   * @return int The size of the collection
+   */
+  public function count() {
+    return $this->size();
+  }
   
   /**
    * Merges two collections together.  If the arrays contain `string` keys, the values
diff --git a/tests/CollectionTest.php b/tests/CollectionTest.php
index 261812d..006066c 100644
--- a/tests/CollectionTest.php
+++ b/tests/CollectionTest.php
@@ -31,7 +31,13 @@ public function testConstructWithContent() {
   
   public function testInstantiator() {
     $collection = new Collection();
-    
     $this->assertInstanceOf(Collection::class, $collection->__new([]));
   }
+  
+  public function testCountable() {
+    $collection = new Collection();
+    $this->assertSame(0, count($collection));
+    $collection = new Collection([1,2,3]);
+    $this->assertSame(3, count($collection));
+  }
 }
diff --git a/tests/ReadOnlyCollectionTest.php b/tests/ReadOnlyCollectionTest.php
index 69420c6..de0a750 100644
--- a/tests/ReadOnlyCollectionTest.php
+++ b/tests/ReadOnlyCollectionTest.php
@@ -34,4 +34,11 @@ public function testInstantiator() {
     
     $this->assertInstanceOf(ReadOnlyCollection::class, $collection->__new([]));
   }
+
+  public function testCountable() {
+    $collection = new ReadOnlyCollection();
+    $this->assertSame(0, count($collection));
+    $collection = new ReadOnlyCollection([1,2,3]);
+    $this->assertSame(3, count($collection));
+  }
 }