diff --git a/.gitignore b/.gitignore
index b7e7725..3476aa5 100644
--- a/.gitignore
+++ b/.gitignore
@@ -7,4 +7,5 @@
 /pkg/
 /spec/reports/
 /tmp/
+/bin/
 *.gem
diff --git a/README.md b/README.md
index fdaffb8..ddcd9a0 100644
--- a/README.md
+++ b/README.md
@@ -102,12 +102,15 @@ webmaster_verifications:
   yandex: 1234
 ```
 
+* `lang` - The locale these tags are marked up in. Of the format `language_TERRITORY`. Default is `en_US`.
+
 The SEO tag will respect the following YAML front matter if included in a post, page, or document:
 
 * `title` - The title of the post, page, or document
 * `description` - A short description of the page's content
 * `image` - URL to an image associated with the post, page, or document (e.g., `/assets/page-pic.jpg`)
 * `author` - Page-, post-, or document-specific author information (see below)
+* `lang` - Page-, post-, or document-specific language information
 
 ## Advanced usage
 
diff --git a/lib/template.html b/lib/template.html
index 1922381..c06665c 100755
--- a/lib/template.html
+++ b/lib/template.html
@@ -97,6 +97,8 @@
   {% assign seo_page_image = seo_page_image | escape %}
 {% endif %}
 
+{% assign seo_page_lang = page.lang | default: site.lang | default: "en_US" %}
+
 {% if seo_tag.title and seo_title %}
   <title>{{ seo_title }}</title>
 {% endif %}
@@ -109,6 +111,8 @@
   <meta name="author" content="{{ seo_author_name }}" />
 {% endif %}
 
+<meta property="og:locale" content="{{ seo_page_lang | replace:'-','_' }}" />
+
 {% if seo_description %}
   <meta name="description" content="{{ seo_description }}" />
   <meta property="og:description" content="{{ seo_description }}" />
@@ -124,7 +128,6 @@
 {% endif %}
 
 {% if seo_page_image %}
-
   <meta property="og:image" content="{{ seo_page_image }}" />
   {% if page.image.height %}
     <meta property="og:image:height" content="{{ page.image.height }}" />
diff --git a/spec/jekyll_seo_tag_spec.rb b/spec/jekyll_seo_tag_spec.rb
index d4593f8..e2bcb0b 100755
--- a/spec/jekyll_seo_tag_spec.rb
+++ b/spec/jekyll_seo_tag_spec.rb
@@ -257,6 +257,7 @@ describe Jekyll::SeoTag do
 <!-- Begin Jekyll SEO tag v#{version} -->
 <title>Foo</title>
 <meta property="og:title" content="Foo" />
+<meta property="og:locale" content="en_US" />
 <link rel="canonical" href="http://example.invalid/page.html" />
 <meta property="og:url" content="http://example.invalid/page.html" />
 <meta property="og:site_name" content="Foo" />
@@ -581,4 +582,38 @@ EOS
       end
     end
   end
+
+  context "with locale" do
+    it "uses en_US when no locale is specified" do
+      expected = %r!<meta property="og:locale" content="en_US" />!
+      expect(output).to match(expected)
+    end
+
+    context "with site.lang" do
+      let(:site)  { make_site("lang" => "en_US") }
+
+      it "uses site.lang if page.lang is not present" do
+        expected = %r!<meta property="og:locale" content="en_US" />!
+        expect(output).to match(expected)
+      end
+
+      context "with page.lang" do
+        let(:page)  { make_page("lang" => "en_UK") }
+
+        it "uses page.lang if both site.lang and page.lang are present" do
+          expected = %r!<meta property="og:locale" content="en_UK" />!
+          expect(output).to match(expected)
+        end
+      end
+    end
+
+    context "with site.lang hyphenated" do
+      let(:site)  { make_site("lang" => "en-US") }
+
+      it "coerces hyphen to underscore" do
+        expected = %r!<meta property="og:locale" content="en_US" />!
+        expect(output).to match(expected)
+      end
+    end
+  end
 end