diff --git a/src/Omnipay/Common/AbstractGateway.php b/src/Omnipay/Common/AbstractGateway.php
index e30228fb..6b588efc 100644
--- a/src/Omnipay/Common/AbstractGateway.php
+++ b/src/Omnipay/Common/AbstractGateway.php
@@ -27,6 +27,11 @@ abstract class AbstractGateway implements GatewayInterface
      */
     protected $httpRequest;
 
+    /**
+     * @var \Omnipay\Common\Metadata\MetadataInterface The metadata instance.
+     */
+    protected $metadata;
+
     /**
      * Create a new gateway instance
      *
@@ -37,6 +42,8 @@ public function __construct(ClientInterface $httpClient = null, HttpRequest $htt
     {
         $this->httpClient = $httpClient ?: $this->getDefaultHttpClient();
         $this->httpRequest = $httpRequest ?: $this->getDefaultHttpRequest();
+        $this->metadata = $this->createMetadata();
+
         $this->initialize();
     }
 
@@ -48,9 +55,12 @@ public function getShortName()
     public function initialize(array $parameters = array())
     {
         $this->parameters = new ParameterBag;
+        $this->registerParameters();
 
-        // set default parameters
-        foreach ($this->getDefaultParameters() as $key => $value) {
+        // Set parameters
+        foreach ($this->getMetadata()->getParameters() as $parameter) {
+            $key = $parameter->getName();
+            $value = $parameter->getDefaultValue();
             if (is_array($value)) {
                 $this->parameters->set($key, reset($value));
             } else {
@@ -214,4 +224,29 @@ protected function getDefaultHttpRequest()
     {
         return HttpRequest::createFromGlobals();
     }
+
+    /**
+     * Registers gateway parameters.
+     * This method is invoked during gateway initialization to
+     * register all available parameters that are exposed to
+     * the client that uses the gateway.
+     */
+    abstract protected function registerParameters();
+
+    /**
+     * Creates the gateway metadata.
+     * This method is invoked during gateway initialization to
+     * register all available parameters that are exposed to
+     * the client that uses the gateway.
+     */
+    abstract protected function createMetadata();
+
+    /**
+     * Returns the gateway metdata.
+     * @return \Omnipay\Common\Metadata\MetadataInterface The metadata instance.
+     */
+    public function getMetadata()
+    {
+        return $this->metadata;
+    }
 }
diff --git a/src/Omnipay/Common/GatewayInterface.php b/src/Omnipay/Common/GatewayInterface.php
index 87bed4b2..93e09c2a 100644
--- a/src/Omnipay/Common/GatewayInterface.php
+++ b/src/Omnipay/Common/GatewayInterface.php
@@ -22,17 +22,6 @@ public function getName();
      */
     public function getShortName();
 
-    /**
-     * Define gateway parameters, in the following format:
-     *
-     * array(
-     *     'username' => '', // string variable
-     *     'testMode' => false, // boolean variable
-     *     'landingPage' => array('billing', 'login'), // enum variable, first item is default
-     * );
-     */
-    public function getDefaultParameters();
-
     /**
      * Initialize gateway with parameters
      */
@@ -53,4 +42,10 @@ public function getParameters();
      * @return \Omnipay\Common\Message\RequestInterface
      */
     public function purchase(array $parameters = array());
+
+    /**
+     * Returns the gateway metdata.
+     * @return \Omnipay\Common\Metadata\MetadataInterface The metadata instance.
+     */
+    public function getMetadata();
 }
diff --git a/src/Omnipay/Common/Metadata/MetadataAbstract.php b/src/Omnipay/Common/Metadata/MetadataAbstract.php
new file mode 100644
index 00000000..133ca849
--- /dev/null
+++ b/src/Omnipay/Common/Metadata/MetadataAbstract.php
@@ -0,0 +1,46 @@
+<?php
+
+namespace Omnipay\Common\Metadata;
+
+/**
+ * MetadataAbstract is the base class to implement gateway metadata.
+ */
+abstract class MetadataAbstract implements MetadataInterface
+{
+    /**
+     * @var array The list of {@link Omnipay\Common\Parameter\Parameter}
+     * instances.
+     */
+    protected $paramaters;
+
+    /**
+     * Class constructor.
+     */
+    public function __construct()
+    {
+        $this->paramaters = array();
+    }
+
+    /**
+     * Adds a new parameter.
+     * @param ParameterInterface $parameter The parameter instance.
+     */
+    public function addParameter($parameter)
+    {
+        $class = new \ReflectionClass($parameter);
+        if($class->implementsInterface('Omnipay\Common\Parameter\ParameterInterface') === false)
+            throw new \RuntimeException('The paramater must implement Omnipay\Common\Parameter\ParameterInterface');
+
+        $this->paramaters[$parameter->getName()] = $parameter;
+        return $this;
+    }
+
+    /**
+     * Returns the list of parameters.
+     * @return array The list of {@link ParameterInterface} instances.
+     */
+    public function getParameters()
+    {
+        return $this->paramaters;
+    }
+}
\ No newline at end of file
diff --git a/src/Omnipay/Common/Metadata/MetadataInterface.php b/src/Omnipay/Common/Metadata/MetadataInterface.php
new file mode 100644
index 00000000..a026932f
--- /dev/null
+++ b/src/Omnipay/Common/Metadata/MetadataInterface.php
@@ -0,0 +1,39 @@
+<?php
+
+namespace Omnipay\Common\Metadata;
+
+/**
+ * MetadataInterface is the interface for gateway metadata.
+ */
+interface MetadataInterface
+{
+    /**
+     * Adds a new parameter.
+     * @param ParameterInterface $parameter The parameter instance.
+     */
+    public function addParameter($parameter);
+
+    /**
+     * Returns the description.
+     * @return string The description.
+     */
+    public function getDescription();
+
+    /**
+     * Returns the name.
+     * @return string The name.
+     */
+    public function getName();
+
+    /**
+     * Returns the list of parameters.
+     * @return array The list of {@link ParameterInterface} instances.
+     */
+    public function getParameters();
+
+    /**
+     * Returns the site.
+     * @return string The site.
+     */
+    public function getSite();
+}
\ No newline at end of file
diff --git a/src/Omnipay/Common/Parameter/Parameter.php b/src/Omnipay/Common/Parameter/Parameter.php
new file mode 100644
index 00000000..f2228167
--- /dev/null
+++ b/src/Omnipay/Common/Parameter/Parameter.php
@@ -0,0 +1,171 @@
+<?php
+
+namespace Omnipay\Common\Parameter;
+
+/**
+ * Parameter is the class for a gateway parameter.
+ */
+class Parameter implements ParameterInterface
+{
+    /**
+     * @var array The list of allowed values.
+     */
+    protected $allowedValues;
+
+    /**
+     * @var mixed The default value if none is set.
+     */
+    protected $defaultValue;
+
+    /**
+     * @var string The description.
+     */
+    protected $description;
+
+    /**
+     * @var string The name.
+     */
+    protected $name;
+
+    /**
+     * @var string The label.
+     */
+    protected $label;
+
+    /**
+     * @var boolean If the parameter is required.
+     */
+    protected $isRequired;
+
+    /**
+     * Class consturctor.
+     * @param string $name The name.
+     */
+    public function __construct($name)
+    {
+        $this->name = $name;
+        $this->allowedValues = array();
+    }
+
+    /**
+     * Returns the list of allowed values.
+     * @return array The list of allowed values.
+     */
+    public function getAllowedValues()
+    {
+        return $this->allowedValues;
+    }
+
+    /**
+     * Returns the default value.
+     * @return mixed The default value.
+     */
+    public function getDefaultValue()
+    {
+        return $this->defaultValue;
+    }
+
+    /**
+     * Returns the description.
+     * @return string The description.
+     */
+    public function getDescription()
+    {
+        return $this->description;
+    }
+
+    /**
+     * Returns the name.
+     * @return string The name.
+     */
+    public function getName()
+    {
+        return $this->name;
+    }
+
+    /**
+     * Returns the label.
+     * @return string The label.
+     */
+    public function getLabel()
+    {
+        return $this->label;
+    }
+
+    /**
+     * Checks if the paramter is required and
+     * its value cannot be empty.
+     * @return boolean True if the parameter is required or
+     * false otherwise.
+     */
+    public function isRequired()
+    {
+        return $this->isRequired;
+    }
+
+    /**
+     * Sets the list of allowed values.
+     * @param array $values The list of allowed values.
+     * @return Parameter The current instance.
+     */
+    public function setAllowedValues($values)
+    {
+        $this->allowedValues = $values;
+        return $this;
+    }
+
+    /**
+     * Sets the default value.
+     * @param mixed $value The default value.
+     * @return Parameter The current instance.
+     */
+    public function setDefaultValue($value)
+    {
+        $this->defaultValue = $value;
+        return $this;
+    }
+
+    /**
+     * Sets the description.
+     * @param string $value The description.
+     * @return Parameter The current instance.
+     */
+    public function setDescription($value)
+    {
+        $this->description = $value;
+        return $this;
+    }
+
+    /**
+     * Sets the name.
+     * @param string $value The name.
+     * @return Parameter The current instance.
+     */
+    public function setName($value)
+    {
+        $this->id = $value;
+        return $this;
+    }
+
+    /**
+     * Sets the label.
+     * @param string $value The label.
+     * @return Parameter The current instance.
+     */
+    public function setLabel($value)
+    {
+        $this->label = $value;
+        return $this;
+    }
+
+    /**
+     * Sets if the parameter is required.
+     * @param boolean $required True if required or false otherwise.
+     * @return Parameter The current instance.
+     */
+    public function setIsRequired($required)
+    {
+        $this->isRequired = $required;
+        return $this;
+    }
+}
\ No newline at end of file
diff --git a/src/Omnipay/Common/Parameter/ParameterInterface.php b/src/Omnipay/Common/Parameter/ParameterInterface.php
new file mode 100644
index 00000000..11cb45cd
--- /dev/null
+++ b/src/Omnipay/Common/Parameter/ParameterInterface.php
@@ -0,0 +1,89 @@
+<?php
+
+namespace Omnipay\Common\Parameter;
+
+/**
+ * ParameterInterface is the base interface for a parameter.
+ */
+interface ParameterInterface
+{
+    /**
+     * Returns the list of allowed values.
+     * @return array The list of allowed values.
+     */
+    public function getAllowedValues();
+
+    /**
+     * Returns the default value.
+     * @return mixed The default value.
+     */
+    public function getDefaultValue();
+
+    /**
+     * Returns the description.
+     * @return string The description.
+     */
+    public function getDescription();
+
+    /**
+     * Returns the label.
+     * @return string The label.
+     */
+    public function getLabel();
+
+    /**
+     * Returns the name.
+     * @return string The name.
+     */
+    public function getName();
+
+    /**
+     * Checks if the paramter is required and
+     * its value cannot be empty.
+     * @return boolean True if the parameter is required or
+     * false otherwise.
+     */
+    public function isRequired();
+
+    /**
+     * Sets the list of allowed values.
+     * @param array $values The list of allowed values.
+     * @return Parameter The current instance.
+     */
+    public function setAllowedValues($values);
+
+    /**
+     * Sets the default value.
+     * @param mixed $value The default value.
+     * @return Parameter The current instance.
+     */
+    public function setDefaultValue($value);
+
+    /**
+     * Sets the description.
+     * @param string $value The description.
+     * @return Parameter The current instance.
+     */
+    public function setDescription($value);
+
+    /**
+     * Sets the name.
+     * @param string $value The name.
+     * @return Parameter The current instance.
+     */
+    public function setName($value);
+
+    /**
+     * Sets the label.
+     * @param string $value The label.
+     * @return Parameter The current instance.
+     */
+    public function setLabel($value);
+
+    /**
+     * Sets if the parameter is required.
+     * @param boolean $required True if required or false otherwise.
+     * @return Parameter The current instance.
+     */
+    public function setIsRequired($required);
+}
\ No newline at end of file
diff --git a/src/Omnipay/PayPal/ExpressGateway.php b/src/Omnipay/PayPal/ExpressGateway.php
index 6de6f7ae..7d649894 100644
--- a/src/Omnipay/PayPal/ExpressGateway.php
+++ b/src/Omnipay/PayPal/ExpressGateway.php
@@ -2,6 +2,7 @@
 
 namespace Omnipay\PayPal;
 
+use Omnipay\Common\Parameter\Parameter;
 use Omnipay\PayPal\Message\ExpressAuthorizeRequest;
 use Omnipay\PayPal\Message\ExpressCompleteAuthorizeRequest;
 use Omnipay\PayPal\Message\ExpressCompletePurchaseRequest;
@@ -16,16 +17,6 @@ public function getName()
         return 'PayPal Express';
     }
 
-    public function getDefaultParameters()
-    {
-        $settings = parent::getDefaultParameters();
-        $settings['solutionType'] = array('Sole', 'Mark');
-        $settings['landingPage'] = array('Billing', 'Login');
-        $settings['headerImageUrl'] = '';
-
-        return $settings;
-    }
-
     public function getSolutionType()
     {
         return $this->getParameter('solutionType');
@@ -84,4 +75,38 @@ public function completePurchase(array $parameters = array())
     {
         return $this->createRequest('\Omnipay\PayPal\Message\ExpressCompletePurchaseRequest', $parameters);
     }
+
+    /**
+     * Registers gateway parameters.
+     */
+    protected function registerParameters()
+    {
+        parent::registerParameters();
+
+        // solutionType parameter
+        $parameter = new Parameter('solutionType');
+        $parameter->setLabel(_('Solution type'))
+            ->setDescription(_('The type of checkout flow'))
+            ->setDefaultValue('Sole')
+            ->setAllowedValues(array('Sole', 'Mark'))
+            ->setIsRequired(true);
+        $this->getMetadata()->addParameter($parameter);
+
+        // landingPage parameter
+        $parameter = new Parameter('landingPage');
+        $parameter->setLabel(_('Landing page'))
+            ->setDescription(_('The type of PayPal page to display'))
+            ->setDefaultValue('Billing')
+            ->setAllowedValues(array('Billing', 'Login'))
+            ->setIsRequired(true);
+        $this->getMetadata()->addParameter($parameter);
+
+        // headerImageUrl parameter
+        $parameter = new Parameter('headerImageUrl');
+        $parameter->setLabel(_('Landing page'))
+            ->setDescription(_('The URL for the image you want to appear at the top left of the payment page'))
+            ->setDefaultValue('')
+            ->setIsRequired(true);
+        $this->getMetadata()->addParameter($parameter);
+    }
 }
diff --git a/src/Omnipay/PayPal/ExpressMetadata.php b/src/Omnipay/PayPal/ExpressMetadata.php
new file mode 100644
index 00000000..9a302fed
--- /dev/null
+++ b/src/Omnipay/PayPal/ExpressMetadata.php
@@ -0,0 +1,38 @@
+<?php
+
+namespace Omnipay\PayPal;
+
+use \Omnipay\Common\Metadata\MetadataAbstract;
+
+/**
+ * Metadata for PayPal Express gateway.
+ */
+class ExpressMetadata extends MetadataAbstract
+{
+    /**
+     * Returns the description.
+     * @return string The description.
+     */
+    public function getDescription()
+    {
+        return 'PayPal Express Checkout is a fast, easy way for buyers to pay with PayPal';
+    }
+
+    /**
+     * Returns the name.
+     * @return string The name.
+     */
+    public function getName()
+    {
+        return 'PayPal Express';
+    }
+
+    /**
+     * Returns the site.
+     * @return string The site.
+     */
+    public function getSite()
+    {
+        return 'https://www.paypal.com/webapps/mpp/express-checkout';
+    }
+}
\ No newline at end of file
diff --git a/src/Omnipay/PayPal/ProGateway.php b/src/Omnipay/PayPal/ProGateway.php
index 2accee74..ba7b96b6 100644
--- a/src/Omnipay/PayPal/ProGateway.php
+++ b/src/Omnipay/PayPal/ProGateway.php
@@ -3,6 +3,7 @@
 namespace Omnipay\PayPal;
 
 use Omnipay\Common\AbstractGateway;
+use Omnipay\Common\Parameter\Parameter;
 use Omnipay\PayPal\Message\ProAuthorizeRequest;
 use Omnipay\PayPal\Message\CaptureRequest;
 use Omnipay\PayPal\Message\RefundRequest;
@@ -76,4 +77,52 @@ public function refund(array $parameters = array())
     {
         return $this->createRequest('\Omnipay\PayPal\Message\RefundRequest', $parameters);
     }
+
+    /**
+     * Creates the gateway metadata.
+     * This method is invoked during gateway initialization to
+     * register all available parameters that are exposed to
+     * the client that uses the gateway.
+     */
+    protected function createMetadata()
+    {
+        return new ProMetadata;
+    }
+
+    /**
+     * Registers gateway parameters.
+     */
+    protected function registerParameters()
+    {
+        // username parameter
+        $parameter = new Parameter('username');
+        $parameter->setLabel(_('Username'))
+            ->setDescription(_('The PayPal username'))
+            ->setDefaultValue('')
+            ->setIsRequired(true);
+        $this->getMetadata()->addParameter($parameter);
+
+        // password parameter
+        $parameter = new Parameter('password');
+        $parameter->setLabel(_('Password'))
+            ->setDescription(_('The PayPal password'))
+            ->setDefaultValue('')
+            ->setIsRequired(true);
+        $this->getMetadata()->addParameter($parameter);
+
+        // signature parameter
+        $parameter = new Parameter('signature');
+        $parameter->setLabel(_('Signature'))
+            ->setDescription(_('The signature'))
+            ->setDefaultValue('')
+            ->setIsRequired(true);
+        $this->getMetadata()->addParameter($parameter);
+
+        // testMode parameter
+        $parameter = new Parameter('testMode');
+        $parameter->setLabel(_('Test mode'))
+            ->setDescription(_('Enable this option to test the gateway'))
+            ->setDefaultValue('')
+            ->setIsRequired(true);
+    }
 }
diff --git a/src/Omnipay/PayPal/ProMetadata.php b/src/Omnipay/PayPal/ProMetadata.php
new file mode 100644
index 00000000..7fe1e1ab
--- /dev/null
+++ b/src/Omnipay/PayPal/ProMetadata.php
@@ -0,0 +1,38 @@
+<?php
+
+namespace Omnipay\PayPal;
+
+use \Omnipay\Common\Metadata\MetadataAbstract;
+
+/**
+ * Metadata for PayPal Pro gateway.
+ */
+class ProMetadata extends MetadataAbstract
+{
+    /**
+     * Returns the description.
+     * @return string The description.
+     */
+    public function getDescription()
+    {
+        return 'PayPal Payments Pro is an affordable website payment processing solution for businesses with 100+ orders/month.';
+    }
+
+    /**
+     * Returns the name.
+     * @return string The name.
+     */
+    public function getName()
+    {
+        return 'PayPal Pro';
+    }
+
+    /**
+     * Returns the site.
+     * @return string The site.
+     */
+    public function getSite()
+    {
+        return 'https://www.paypal.com/webapps/mpp/paypal-payments-pro';
+    }
+}
\ No newline at end of file