diff --git a/src/Bigcommerce/Api/Client.php b/src/Bigcommerce/Api/Client.php
index 00eb60f..a31a048 100644
--- a/src/Bigcommerce/Api/Client.php
+++ b/src/Bigcommerce/Api/Client.php
@@ -242,9 +242,9 @@ public static function getConnection()
     /**
      * Set the HTTP connection object. DANGER: This can screw up your Client!
      *
-     * @param Connection $connection The connection to use
+     * @param ConnectionInterface $connection The connection to use
      */
-    public static function setConnection(Connection $connection = null)
+    public static function setConnection(ConnectionInterface $connection = null)
     {
         self::$connection = $connection;
     }
diff --git a/src/Bigcommerce/Api/Connection.php b/src/Bigcommerce/Api/Connection.php
index c333d67..08b5ead 100644
--- a/src/Bigcommerce/Api/Connection.php
+++ b/src/Bigcommerce/Api/Connection.php
@@ -5,7 +5,7 @@
 /**
  * HTTP connection.
  */
-class Connection
+class Connection implements ConnectionInterface
 {
     /**
      * XML media type.
diff --git a/src/Bigcommerce/Api/ConnectionInterface.php b/src/Bigcommerce/Api/ConnectionInterface.php
new file mode 100644
index 0000000..dfaa2e0
--- /dev/null
+++ b/src/Bigcommerce/Api/ConnectionInterface.php
@@ -0,0 +1,119 @@
+<?php
+
+namespace Bigcommerce\Api;
+
+interface ConnectionInterface
+{
+    /**
+     * Throw an exception if the request encounters an HTTP error condition.
+     *
+     * <p>An error condition is considered to be:</p>
+     *
+     * <ul>
+     *    <li>400-499 - Client error</li>
+     *    <li>500-599 - Server error</li>
+     * </ul>
+     *
+     * <p><em>Note that this doesn't use the builtin CURL_FAILONERROR option,
+     * as this fails fast, making the HTTP body and headers inaccessible.</em></p>
+     *
+     * @param bool $option the new state of this feature
+     */
+    public function failOnError($option);
+
+    /**
+     * Controls whether requests and responses should be treated
+     * as XML. Defaults to false (using JSON).
+     *
+     * @param bool $option the new state of this feature
+     */
+    public function useXml($option);
+
+    /**
+     * @param boolean
+     */
+    public function verifyPeer($option);
+
+    /**
+     * Add a custom header to the request.
+     *
+     * @param string $header
+     * @param string $value
+     */
+    public function addHeader($header, $value);
+
+    /**
+     * Remove a header from the request.
+     *
+     * @param string $header
+     */
+    public function removeHeader($header);
+
+    /**
+     * Return an representation of an error returned by the last request, or false
+     * if the last request was not an error.
+     */
+    public function getLastError();
+
+    /**
+     * Make an HTTP GET request to the specified endpoint.
+     *
+     * @param string $url URL to retrieve
+     * @param array|bool $query Optional array of query string parameters
+     *
+     * @return mixed
+     */
+    public function get($url, $query);
+
+    /**
+     * Make an HTTP POST request to the specified endpoint.
+     *
+     * @param string $url URL to which we send the request
+     * @param mixed $body Data payload (JSON string or raw data)
+     *
+     * @return mixed
+     */
+    public function post($url, $body);
+
+    /**
+     * Make an HTTP HEAD request to the specified endpoint.
+     *
+     * @param string $url URL to which we send the request
+     * @return mixed
+     */
+    public function head($url);
+
+    /**
+     * Make an HTTP PUT request to the specified endpoint.
+     *
+     * Requires a tmpfile() handle to be opened on the system, as the cURL
+     * API requires it to send data.
+     *
+     * @param string $url URL to which we send the request
+     * @param mixed $body Data payload (JSON string or raw data)
+     * @return mixed
+     */
+    public function put($url, $body);
+
+    /**
+     * Make an HTTP DELETE request to the specified endpoint.
+     *
+     * @param string $url URL to which we send the request
+     * @return mixed
+     */
+    public function delete($url);
+
+    /**
+     * Access given header from the response.
+     *
+     * @param string $header Header name to retrieve
+     *
+     * @return string|void
+     */
+    public function getHeader($header);
+
+    /**
+     * Return the full list of response headers
+     */
+    public function getHeaders();
+}