diff --git a/src/Response/Card/CardTypes.php b/src/Response/Card/CardTypes.php
new file mode 100644
index 0000000..244ca12
--- /dev/null
+++ b/src/Response/Card/CardTypes.php
@@ -0,0 +1,19 @@
+<?php
+
+namespace Alexa\Response\Card;
+
+/**
+ * Class CardTypes
+ *
+ * Enumeration of the allowed Alexa card types
+ *
+ * @package Alexa\Response\Card
+ */
+abstract class CardTypes
+{
+    // Constants
+
+    const TYPE_SIMPLE = 'Simple';
+    const TYPE_STANDARD = 'Standard';
+    const TYPE_LINK_ACCOUNT = 'LinkAccount';
+}
diff --git a/src/Response/Card/LinkAccountCard.php b/src/Response/Card/LinkAccountCard.php
index 0aa4a09..202c5c6 100644
--- a/src/Response/Card/LinkAccountCard.php
+++ b/src/Response/Card/LinkAccountCard.php
@@ -3,6 +3,7 @@
 namespace Alexa\Response\Card;
 
 use Alexa\Response\Card\CardInterface;
+use Alexa\Response\Card\CardTypes;
 
 /**
  * Class LinkAccountCard
@@ -13,10 +14,6 @@
  */
 class LinkAccountCard implements CardInterface
 {
-    // Constants
-
-    const CARD_TYPE = 'LinkAccount';
-
     // Public Methods
 
     /**
@@ -27,7 +24,7 @@ class LinkAccountCard implements CardInterface
     public function render()
     {
         return [
-            'type' => self::CARD_TYPE
+            'type' => CardTypes::TYPE_LINK_ACCOUNT
         ];
     }
 }
diff --git a/src/Response/Card/SimpleCard.php b/src/Response/Card/SimpleCard.php
index 001d22d..1ec4e29 100644
--- a/src/Response/Card/SimpleCard.php
+++ b/src/Response/Card/SimpleCard.php
@@ -3,6 +3,7 @@
 namespace Alexa\Response\Card;
 
 use Alexa\Response\Card\CardInterface;
+use Alexa\Response\Card\CardTypes;
 
 /**
  * Class SimpleCard
@@ -15,8 +16,6 @@ class SimpleCard implements CardInterface
 {
     // Constants
 
-    const CARD_TYPE = 'Simple';
-
     const ERROR_TITLE_NOT_SET = 'You must provide a title for the card';
     const ERROR_CONTENT_NOT_SET = 'You must provide the content for the card';
 
@@ -55,7 +54,7 @@ public function __construct($title, $content)
     public function render()
     {
         return [
-            'type' => self::CARD_TYPE,
+            'type' => CardTypes::TYPE_SIMPLE,
             'title' => $this->getTitle(),
             'content' => $this->getContent()
         ];
diff --git a/src/Response/Card/StandardCard.php b/src/Response/Card/StandardCard.php
index d3a04d9..0a7e556 100644
--- a/src/Response/Card/StandardCard.php
+++ b/src/Response/Card/StandardCard.php
@@ -3,6 +3,7 @@
 namespace Alexa\Response\Card;
 
 use Alexa\Response\Card\CardInterface;
+use Alexa\Response\Card\CardTypes;
 
 /**
  * Class StandardCard
@@ -15,8 +16,6 @@ class StandardCard implements CardInterface
 {
     // Constants
 
-    const CARD_TYPE = 'Standard';
-
     const ERROR_TITLE_NOT_SET = 'You must provide a title.';
     const ERROR_TEXT_NOT_SET = 'You must provide card text.';
     const ERROR_SMALL_IMAGE_URL_NOT_SET = 'You must provide a small image URL.';
@@ -67,7 +66,7 @@ public function __construct($title, $text, $smallImageUrl, $largeImageUrl)
     public function render()
     {
         return [
-            'type' => self::CARD_TYPE,
+            'type' => CardTypes::TYPE_STANDARD,
             'title' => $this->getTitle(),
             'text' => $this->getText(),
             'image' => [
diff --git a/src/Response/OutputSpeech/OutputSpeechTypes.php b/src/Response/OutputSpeech/OutputSpeechTypes.php
new file mode 100644
index 0000000..4d6f531
--- /dev/null
+++ b/src/Response/OutputSpeech/OutputSpeechTypes.php
@@ -0,0 +1,18 @@
+<?php
+
+namespace Alexa\Response\OutputSpeech;
+
+/**
+ * Class OutputSpeechTypes
+ *
+ * Enumeration of the allowed OutputSpeech types
+ *
+ * @package Alexa\Response\OutputSpeech
+ */
+abstract class OutputSpeechTypes
+{
+    // Constants
+
+    const TYPE_PLAIN_TEXT = 'PlainText';
+    const TYPE_SSML = 'SSML';
+}
diff --git a/src/Response/OutputSpeech/PlainTextOutputSpeech.php b/src/Response/OutputSpeech/PlainTextOutputSpeech.php
index 4f979ef..6e9883d 100644
--- a/src/Response/OutputSpeech/PlainTextOutputSpeech.php
+++ b/src/Response/OutputSpeech/PlainTextOutputSpeech.php
@@ -3,6 +3,7 @@
 namespace Alexa\Response\OutputSpeech;
 
 use Alexa\Response\OutputSpeech\OutputSpeechInterface;
+use Alexa\Response\OutputSpeech\OutputSpeechTypes;
 
 /**
  * Class PlainTextOutputSpeech
@@ -15,8 +16,6 @@ class PlainTextOutputSpeech implements OutputSpeechInterface
 {
     // Constants
 
-    const OUTPUT_SPEECH_TYPE = 'PlainText';
-
     const ERROR_TEXT_NOT_SET  = 'You must provide output speech text.';
 
     // Fields
@@ -49,7 +48,7 @@ public function __construct($text)
     public function render()
     {
         return [
-            'type' => self::OUTPUT_SPEECH_TYPE,
+            'type' => OutputSpeechTypes::TYPE_PLAIN_TEXT,
             'text' => $this->getText()
         ];
     }
diff --git a/src/Response/OutputSpeech/SsmlOutputSpeech.php b/src/Response/OutputSpeech/SsmlOutputSpeech.php
index 1376e1c..48986f7 100644
--- a/src/Response/OutputSpeech/SsmlOutputSpeech.php
+++ b/src/Response/OutputSpeech/SsmlOutputSpeech.php
@@ -3,6 +3,7 @@
 namespace Alexa\Response\OutputSpeech;
 
 use Alexa\Response\OutputSpeech\OutputSpeechInterface;
+use Alexa\Response\OutputSpeech\OutputSpeechTypes;
 
 /**
  * Class SsmlOutputSpeech
@@ -15,8 +16,6 @@ class SsmlOutputSpeech implements OutputSpeechInterface
 {
     // Constants
 
-    const OUTPUT_SPEECH_TYPE_SSML = 'SSML';
-
     const ERROR_SSML_NOT_SET  = 'You must provide output speech SSML.';
 
     // Fields
@@ -46,7 +45,7 @@ public function __construct($ssml)
     public function render()
     {
         return [
-            'type' => self::OUTPUT_SPEECH_TYPE_SSML,
+            'type' => OutputSpeechTypes::TYPE_SSML,
             'ssml' => $this->getSsml()
         ];
     }