diff --git a/src/Message/Response.php b/src/Message/Response.php
new file mode 100644
index 0000000..2029698
--- /dev/null
+++ b/src/Message/Response.php
@@ -0,0 +1,153 @@
+<?php
+
+namespace WellRESTed\Message;
+
+use Psr\Http\Message\ResponseInterface;
+use Psr\Http\Message\StreamableInterface;
+
+class Response extends Message implements ResponseInterface
+{
+    /**
+     * Text explanation of the HTTP Status Code. You only need to set this if
+     * you are using nonstandard status codes. Otherwise, the instance will
+     * set the when you update the status code.
+     *
+     * @var string
+     */
+    private $reasonPhrase;
+    /** @var int  HTTP status code */
+    private $statusCode;
+    /** @var string HTTP protocol and version */
+
+    // Psr\Http\Message\ResponseInterface ------------------------------------------------------------------------------
+
+    /**
+     * Gets the response Status-Code.
+     *
+     * The Status-Code is a 3-digit integer result code of the server's attempt
+     * to understand and satisfy the request.
+     *
+     * @return integer Status code.
+     */
+    public function getStatusCode()
+    {
+        return $this->statusCode;
+    }
+
+    /**
+     * Create a new instance with the specified status code, and optionally
+     * reason phrase, for the response.
+     *
+     * If no Reason-Phrase is specified, implementations MAY choose to default
+     * to the RFC 7231 or IANA recommended reason phrase for the response's
+     * Status-Code.
+     *
+     * This method MUST be implemented in such a way as to retain the
+     * immutability of the message, and MUST return a new instance that has the
+     * updated status and reason phrase.
+     *
+     * @link http://tools.ietf.org/html/rfc7231#section-6
+     * @link http://www.iana.org/assignments/http-status-codes/http-status-codes.xhtml
+     * @param integer $code The 3-digit integer result code to set.
+     * @param null|string $reasonPhrase The reason phrase to use with the
+     *     provided status code; if none is provided, implementations MAY
+     *     use the defaults as suggested in the HTTP specification.
+     * @return self
+     * @throws \InvalidArgumentException For invalid status code arguments.
+     */
+    public function withStatus($code, $reasonPhrase = null)
+    {
+        $response = clone $this;
+        $response->statusCode = $code;
+        if ($reasonPhrase === null) {
+            static $reasonPhraseLookup = null;
+            if ($reasonPhraseLookup === null) {
+                $reasonPhraseLookup = [
+                    100 => "Continue",
+                    101 => "Switching Protocols",
+                    102 => "Processing",
+                    200 => "OK",
+                    201 => "Created",
+                    202 => "Accepted",
+                    203 => "Non-Authoritative Information",
+                    204 => "No Content",
+                    205 => "Reset Content",
+                    206 => "Partial Content",
+                    207 => "Multi-Status",
+                    208 => "Already Reported",
+                    226 => "IM Used",
+                    300 => "Multiple Choices",
+                    301 => "Moved Permanently",
+                    302 => "Found",
+                    303 => "See Other",
+                    304 => "Not Modified",
+                    305 => "Use Proxy",
+                    307 => "Temporary Redirect",
+                    308 => "Permanent Redirect",
+                    400 => "Bad Request",
+                    401 => "Unauthorized",
+                    402 => "Payment Required",
+                    403 => "Forbidden",
+                    404 => "Not Found",
+                    405 => "Method Not Allowed",
+                    406 => "Not Acceptable",
+                    407 => "Proxy Authentication Required",
+                    408 => "Request Timeout",
+                    409 => "Conflict",
+                    410 => "Gone",
+                    411 => "Length Required",
+                    412 => "Precondition Failed",
+                    413 => "Payload Too Large",
+                    414 => "URI Too Long",
+                    415 => "Unsupported Media Type",
+                    416 => "Range Not Satisfiable",
+                    417 => "Expectation Failed",
+                    421 => "Misdirected Request",
+                    422 => "Unprocessable Entity",
+                    423 => "Locked",
+                    424 => "Failed Dependency",
+                    426 => "Upgrade Required",
+                    428 => "Precondition Required",
+                    429 => "Too Many Requests",
+                    431 => "Request Header Fields Too Large",
+                    500 => "Internal Server Error",
+                    501 => "Not Implemented",
+                    502 => "Bad Gateway",
+                    503 => "Service Unavailable",
+                    504 => "Gateway Timeout",
+                    505 => "HTTP Version Not Supported",
+                    506 => "Variant Also Negotiates",
+                    507 => "Insufficient Storage",
+                    508 => "Loop Detected",
+                    510 => "Not Extended",
+                    511 => "Network Authentication Required"
+                ];
+            }
+            if (isset($reasonPhraseLookup[$code])) {
+                $reasonPhrase = $reasonPhraseLookup[$code];
+            } else {
+                $reasonPhrase = "Unknown";
+            }
+        }
+        $response->reasonPhrase = $reasonPhrase;
+        return $response;
+    }
+
+    /**
+     * Gets the response Reason-Phrase, a short textual description of the Status-Code.
+     *
+     * Because a Reason-Phrase is not a required element in a response
+     * Status-Line, the Reason-Phrase value MAY be null. Implementations MAY
+     * choose to return the default RFC 7231 recommended reason phrase (or those
+     * listed in the IANA HTTP Status Code Registry) for the response's
+     * Status-Code.
+     *
+     * @link http://tools.ietf.org/html/rfc7231#section-6
+     * @link http://www.iana.org/assignments/http-status-codes/http-status-codes.xhtml
+     * @return string|null Reason phrase, or null if unknown.
+     */
+    public function getReasonPhrase()
+    {
+        return $this->reasonPhrase;
+    }
+}
diff --git a/test/tests/unit/Message/ResponseTest.php b/test/tests/unit/Message/ResponseTest.php
new file mode 100644
index 0000000..923807e
--- /dev/null
+++ b/test/tests/unit/Message/ResponseTest.php
@@ -0,0 +1,106 @@
+<?php
+
+namespace WellRESTed\Test\Unit\Message;
+
+use WellRESTed\Message\Response;
+
+class ResponseTest extends \PHPUnit_Framework_TestCase
+{
+    /**
+     * @covers WellRESTed\Message\Response::withStatus
+     * @covers WellRESTed\Message\Response::getStatusCode
+     * @uses   WellRESTed\Message\Response::__clone
+     * @uses   WellRESTed\Message\Message
+     * @uses   WellRESTed\Message\HeaderCollection
+     */
+    public function testCreatesNewInstanceWithStatusCode()
+    {
+        $response = new Response();
+        $copy = $response->withStatus(200);
+        $this->assertEquals(200, $copy->getStatusCode());
+    }
+
+    /**
+     * @covers WellRESTed\Message\Response::withStatus
+     * @covers WellRESTed\Message\Response::getReasonPhrase
+     * @uses   WellRESTed\Message\Response::__clone
+     * @uses   WellRESTed\Message\Message
+     * @uses   WellRESTed\Message\HeaderCollection
+     * @dataProvider statusProvider
+     */
+    public function testCreatesNewInstanceWithReasonPhrase($code, $reasonPhrase, $expected)
+    {
+        $response = new Response();
+        $copy = $response->withStatus($code, $reasonPhrase);
+        $this->assertEquals($expected, $copy->getReasonPhrase());
+    }
+
+    public function statusProvider()
+    {
+        return [
+            [100, null, "Continue"],
+            [101, null, "Switching Protocols"],
+            [200, null, "OK"],
+            [201, null, "Created"],
+            [202, null, "Accepted"],
+            [203, null, "Non-Authoritative Information"],
+            [204, null, "No Content"],
+            [205, null, "Reset Content"],
+            [206, null, "Partial Content"],
+            [300, null, "Multiple Choices"],
+            [301, null, "Moved Permanently"],
+            [302, null, "Found"],
+            [303, null, "See Other"],
+            [304, null, "Not Modified"],
+            [305, null, "Use Proxy"],
+            [400, null, "Bad Request"],
+            [401, null, "Unauthorized"],
+            [402, null, "Payment Required"],
+            [403, null, "Forbidden"],
+            [404, null, "Not Found"],
+            [405, null, "Method Not Allowed"],
+            [406, null, "Not Acceptable"],
+            [407, null, "Proxy Authentication Required"],
+            [408, null, "Request Timeout"],
+            [409, null, "Conflict"],
+            [410, null, "Gone"],
+            [411, null, "Length Required"],
+            [412, null, "Precondition Failed"],
+            [413, null, "Payload Too Large"],
+            [414, null, "URI Too Long"],
+            [415, null, "Unsupported Media Type"],
+            [500, null, "Internal Server Error"],
+            [501, null, "Not Implemented"],
+            [502, null, "Bad Gateway"],
+            [503, null, "Service Unavailable"],
+            [504, null, "Gateway Timeout"],
+            [505, null, "HTTP Version Not Supported"],
+            [598, null, "Unknown"],
+            [599, "Nonstandard", "Nonstandard"]
+        ];
+    }
+
+    /**
+     * @covers WellRESTed\Message\Response::withStatus
+     * @covers WellRESTed\Message\Response::getStatusCode
+     * @uses   WellRESTed\Message\Response::__clone
+     * @uses   WellRESTed\Message\Message
+     * @uses   WellRESTed\Message\HeaderCollection
+     */
+    public function testWithStatusCodePreservesOriginalResponse()
+    {
+        $response1 = new Response();
+        $response1 = $response1->withStatus(200);
+        $response1 = $response1->withHeader("Content-type", "application/json");
+
+        $response2 = $response1->withStatus(404);
+        $response2 = $response2->withHeader("Content-type", "text/plain");
+
+
+        $this->assertEquals(200, $response1->getStatusCode());
+        $this->assertEquals("application/json", $response1->getHeader("Content-type"));
+
+        $this->assertEquals(404, $response2->getStatusCode());
+        $this->assertEquals("text/plain", $response2->getHeader("Content-type"));
+    }
+}