diff --git a/src/Widop/Twitter/Options/OptionBag.php b/src/Widop/Twitter/Options/OptionBag.php
index 972fcae..db77628 100644
--- a/src/Widop/Twitter/Options/OptionBag.php
+++ b/src/Widop/Twitter/Options/OptionBag.php
@@ -16,9 +16,9 @@
  *
  * @author GeLo <geloen.eric@gmail.com>
  */
-class OptionBag implements \ArrayAccess, \IteratorAggregate
+class OptionBag implements OptionBagInterface
 {
-    /** @var \Widop\Twitter\Options\OptionFactory */
+    /** @var \Widop\Twitter\Options\OptionFactoryInterface */
     private $factory;
 
     /** @var array */
@@ -29,7 +29,7 @@ class OptionBag implements \ArrayAccess, \IteratorAggregate
      *
      * @param \Widop\Twitter\Options\OptionFactory|null $factory The option factory.
      */
-    public function __construct(OptionFactory $factory = null)
+    public function __construct(OptionFactoryInterface $factory = null)
     {
         $this->factory = $factory ?: new OptionFactory();
         $this->options = array();
diff --git a/src/Widop/Twitter/Options/OptionBagFactory.php b/src/Widop/Twitter/Options/OptionBagFactory.php
new file mode 100644
index 0000000..2ae47a4
--- /dev/null
+++ b/src/Widop/Twitter/Options/OptionBagFactory.php
@@ -0,0 +1,47 @@
+<?php
+
+/*
+ * This file is part of the Wid'op package.
+ *
+ * (c) Wid'op <contact@widop.com>
+ *
+ * For the full copyright and license information, please read the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Widop\Twitter\Options;
+
+class OptionBagFactory implements OptionBagFactoryInterface
+{
+    /** @var string */
+    private $class;
+
+    /**
+     * Creates an option bag factory.
+     *
+     * @param string $class A fully-qualified classname that implements OptionBagInterface
+     *
+     * @throws \InvalidArgumentException If the supplied classname does not implement OptionBagInterface
+     */
+    public function __construct($class = "Widop\\Twitter\\Options\\OptionBag")
+    {
+        if (!in_array("Widop\\Twitter\\Options\\OptionBagInterface", class_implements($class))) {
+            throw new \InvalidArgumentException(sprintf('The class "%s" does not implement the required interface.', $class));
+        }
+
+        $this->class = $class;
+    }
+
+    /**
+     * Creates an option bag.
+     *
+     * @param \Widop\Twitter\Options\OptionFactoryInterface A factory that creates options.
+     *
+     * @return \Widop\Twitter\Options\OptionBagInterface The option bag.
+     */
+    public function create(OptionFactoryInterface $factory = null)
+    {
+        $class = $this->class;
+        return new $class($factory);
+    }
+}
diff --git a/src/Widop/Twitter/Options/OptionBagFactoryInterface.php b/src/Widop/Twitter/Options/OptionBagFactoryInterface.php
new file mode 100644
index 0000000..f9c3cf7
--- /dev/null
+++ b/src/Widop/Twitter/Options/OptionBagFactoryInterface.php
@@ -0,0 +1,24 @@
+<?php
+
+/*
+ * This file is part of the Wid'op package.
+ *
+ * (c) Wid'op <contact@widop.com>
+ *
+ * For the full copyright and license information, please read the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Widop\Twitter\Options;
+
+interface OptionBagFactoryInterface
+{
+    /**
+     * Creates an option bag.
+     *
+     * @param \Widop\Twitter\Options\OptionFactoryInterface A factory that creates options.
+     *
+     * @return \Widop\Twitter\Options\OptionBagInterface The option bag.
+     */
+    public function create(OptionFactoryInterface $factory = null);
+}
diff --git a/src/Widop/Twitter/Options/OptionBagInterface.php b/src/Widop/Twitter/Options/OptionBagInterface.php
new file mode 100644
index 0000000..ead9f81
--- /dev/null
+++ b/src/Widop/Twitter/Options/OptionBagInterface.php
@@ -0,0 +1,27 @@
+<?php
+
+/*
+ * This file is part of the Wid'op package.
+ *
+ * (c) Wid'op <contact@widop.com>
+ *
+ * For the full copyright and license information, please read the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Widop\Twitter\Options;
+
+interface OptionBagInterface extends \ArrayAccess, \IteratorAggregate
+{
+    /**
+     * Registers an option.
+     *
+     * @param string|\Widop\Twitter\Options\OptionInterface $option The option.
+     * @param string                                        $type   The option type.
+     *
+     * @throws \InvalidArgumentException If the option is not valid.
+     *
+     * @return \Widop\Twitter\Options\OptionBag The option bag.
+     */
+    public function register($option, $type = OptionInterface::TYPE_GET);
+}
diff --git a/src/Widop/Twitter/Options/OptionFactory.php b/src/Widop/Twitter/Options/OptionFactory.php
index 3cb55d6..2189624 100644
--- a/src/Widop/Twitter/Options/OptionFactory.php
+++ b/src/Widop/Twitter/Options/OptionFactory.php
@@ -11,14 +11,12 @@
 
 namespace Widop\Twitter\Options;
 
-use Widop\Twitter\Options\OptionInterface;
-
 /**
  * Option factory.
  *
  * @author GeLo <geloen.eric@gmail.com>
  */
-class OptionFactory
+class OptionFactory implements OptionFactoryInterface
 {
     /** @var array */
     private $mapping;
diff --git a/src/Widop/Twitter/Options/OptionFactoryInterface.php b/src/Widop/Twitter/Options/OptionFactoryInterface.php
new file mode 100644
index 0000000..e584197
--- /dev/null
+++ b/src/Widop/Twitter/Options/OptionFactoryInterface.php
@@ -0,0 +1,29 @@
+<?php
+
+/*
+ * This file is part of the Wid'op package.
+ *
+ * (c) Wid'op <contact@widop.com>
+ *
+ * For the full copyright and license information, please read the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Widop\Twitter\Options;
+
+use Widop\Twitter\Options\OptionInterface;
+
+interface OptionFactoryInterface
+{
+    /**
+     * Creates an option.
+     *
+     * @param string $option The option name.
+     * @param string $type   The option type.
+     *
+     * @throws \InvalidArgumentException If the option does not exist.
+     *
+     * @return \Widop\Twitter\Options\OptionInterface The option.
+     */
+    public function create($option, $type = OptionInterface::TYPE_GET);
+}
diff --git a/tests/Widop/Tests/Twitter/Options/OptionBagFactoryTest.php b/tests/Widop/Tests/Twitter/Options/OptionBagFactoryTest.php
new file mode 100644
index 0000000..b801eca
--- /dev/null
+++ b/tests/Widop/Tests/Twitter/Options/OptionBagFactoryTest.php
@@ -0,0 +1,57 @@
+<?php
+
+/*
+ * This file is part of the Wid'op package.
+ *
+ * (c) Wid'op <contact@widop.com>
+ *
+ * For the full copyright and license information, please read the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Widop\Tests\Twitter\Options;
+
+use Widop\Twitter\Options\OptionBagFactory;
+
+/**
+ * Option factory test.
+ *
+ * @author GeLo <geloen.eric@gmail.com>
+ */
+class OptionBagFactoryTest extends \PHPUnit_Framework_TestCase
+{
+    /** @var \Widop\Twitter\Options\OptionBagFactory */
+    private $optionBagFactory;
+
+    /**
+     * {@inheritdoc}
+     */
+    protected function setUp()
+    {
+        $this->optionBagFactory = new OptionBagFactory();
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    protected function tearDown()
+    {
+        unset($this->optionBagFactory);
+    }
+
+    public function testCreate()
+    {
+        $optionBag = $this->optionBagFactory->create();
+        $this->assertInstanceOf('Widop\Twitter\Options\OptionBag', $optionBag);
+        $this->assertInstanceOf('Widop\Twitter\Options\OptionBagInterface', $optionBag);
+    }
+
+    /**
+     * @expectedException \InvalidArgumentException
+     * @expectedExceptionMessage The class "Widop\Twitter\Options\OptionFactory" does not implement the required interface.
+     */
+    public function testCreateWithNonImplementingClass()
+    {
+        new OptionBagFactory('Widop\Twitter\Options\OptionFactory');
+    }
+}
diff --git a/tests/Widop/Tests/Twitter/Options/OptionFactoryTest.php b/tests/Widop/Tests/Twitter/Options/OptionFactoryTest.php
index d01ea3c..a7646b5 100644
--- a/tests/Widop/Tests/Twitter/Options/OptionFactoryTest.php
+++ b/tests/Widop/Tests/Twitter/Options/OptionFactoryTest.php
@@ -41,7 +41,9 @@ protected function tearDown()
 
     public function testCreate()
     {
-        $this->assertInstanceOf('Widop\Twitter\Options\AccuracyOption', $this->optionFactory->create('accuracy'));
+        $option = $this->optionFactory->create('accuracy');
+        $this->assertInstanceOf('Widop\Twitter\Options\AccuracyOption', $option);
+        $this->assertInstanceOf('Widop\Twitter\Options\OptionInterface', $option);
     }
 
     /**