diff --git a/src/Facebook/InstantArticles/Elements/Caption.php b/src/Facebook/InstantArticles/Elements/Caption.php
index 8776f89a..e08d0813 100644
--- a/src/Facebook/InstantArticles/Elements/Caption.php
+++ b/src/Facebook/InstantArticles/Elements/Caption.php
@@ -37,6 +37,7 @@
 class Caption extends FormattedText
 {
     // Font size
+    const SIZE_SMALL = 'op-small';
     const SIZE_MEDIUM = 'op-medium';
     const SIZE_LARGE = 'op-large';
     const SIZE_XLARGE = 'op-extra-large';
@@ -72,7 +73,7 @@ class Caption extends FormattedText
     private $credit;
 
     /**
-     * @var string text Size. Values: "op-medium"|"op-large"|"op-extra-large"
+     * @var string text Size. Values: "op-small"|"op-medium"|"op-large"|"op-extra-large"
      */
     private $fontSize;
 
@@ -161,6 +162,7 @@ public function withCredit($credit)
     /**
      * The Fontsize that will be used.
      *
+     * @see Caption::SIZE_SMALL
      * @see Caption::SIZE_MEDIUM
      * @see Caption::SIZE_LARGE
      * @see Caption::SIZE_XLARGE
@@ -176,7 +178,8 @@ public function withFontsize($font_size)
             [
                 Caption::SIZE_XLARGE,
                 Caption::SIZE_LARGE,
-                Caption::SIZE_MEDIUM
+                Caption::SIZE_MEDIUM,
+                Caption::SIZE_SMALL
             ]
         );
         $this->fontSize = $font_size;
@@ -301,6 +304,7 @@ public function getCredit()
     /**
      * @return string the Font size.
      *
+     * @see Caption::SIZE_SMALL
      * @see Caption::SIZE_MEDIUM
      * @see Caption::SIZE_LARGE
      * @see Caption::SIZE_XLARGE
diff --git a/src/Facebook/InstantArticles/Transformer/Rules/CaptionRule.php b/src/Facebook/InstantArticles/Transformer/Rules/CaptionRule.php
index 03de4b87..070e0768 100644
--- a/src/Facebook/InstantArticles/Transformer/Rules/CaptionRule.php
+++ b/src/Facebook/InstantArticles/Transformer/Rules/CaptionRule.php
@@ -53,6 +53,7 @@ public static function createFrom($configuration)
                 Caption::ALIGN_CENTER,
                 Caption::ALIGN_RIGHT,
 
+                Caption::SIZE_SMALL,
                 Caption::SIZE_MEDIUM,
                 Caption::SIZE_LARGE,
                 Caption::SIZE_XLARGE,
@@ -90,6 +91,9 @@ public function apply($transformer, $container_of_caption, $node)
             $caption->withTextAlignment(Caption::ALIGN_RIGHT);
         }
 
+        if ($this->getProperty(Caption::SIZE_SMALL, $node)) {
+            $caption->withFontsize(Caption::SIZE_SMALL);
+        }
         if ($this->getProperty(Caption::SIZE_MEDIUM, $node)) {
             $caption->withFontsize(Caption::SIZE_MEDIUM);
         }
diff --git a/src/Facebook/InstantArticles/Transformer/Rules/H1Rule.php b/src/Facebook/InstantArticles/Transformer/Rules/H1Rule.php
index 41327ec3..2b259061 100644
--- a/src/Facebook/InstantArticles/Transformer/Rules/H1Rule.php
+++ b/src/Facebook/InstantArticles/Transformer/Rules/H1Rule.php
@@ -41,6 +41,7 @@ public static function createFrom($configuration)
                 Caption::ALIGN_CENTER,
                 Caption::ALIGN_RIGHT,
 
+                Caption::SIZE_SMALL,
                 Caption::SIZE_MEDIUM,
                 Caption::SIZE_LARGE,
                 Caption::SIZE_XLARGE
diff --git a/tests/Facebook/InstantArticles/Elements/CaptionTest.php b/tests/Facebook/InstantArticles/Elements/CaptionTest.php
index 97c4ed01..336c627b 100644
--- a/tests/Facebook/InstantArticles/Elements/CaptionTest.php
+++ b/tests/Facebook/InstantArticles/Elements/CaptionTest.php
@@ -85,7 +85,7 @@ public function testRenderWithPosition()
         $this->assertEquals($expected, $rendered);
     }
 
-    public function testRenderWithFontSize()
+    public function testRenderWithLargeFontSize()
     {
         $caption =
             Caption::create()
@@ -101,6 +101,22 @@ public function testRenderWithFontSize()
         $this->assertEquals($expected, $rendered);
     }
 
+    public function testRenderWithSmallFontSize()
+    {
+        $caption =
+            Caption::create()
+                ->appendText('Small Caption Title')
+                ->withFontsize(Caption::SIZE_SMALL);
+
+        $expected =
+            '<figcaption class="op-small">'.
+                'Small Caption Title'.
+            '</figcaption>';
+
+        $rendered = $caption->render();
+        $this->assertEquals($expected, $rendered);
+    }
+
     public function testRenderWithTextAlignment()
     {
         $caption =