diff --git a/spec/shadow/index.html b/spec/shadow/index.html
index 9b1d5f7a..54f078e3 100644
--- a/spec/shadow/index.html
+++ b/spec/shadow/index.html
@@ -1116,6 +1116,20 @@ <h3>Ranges and Selections</h3>
         <p>The <code>getSelection()</code> method of the <a>shadow root</a> object returns the current <a>selection</a> in this <a>shadow tree</a>.</p>
       </section>
 
+      <section>
+        <h3>Focus</h3>
+      <p>A <a>shadow host</a> can delegate focus to its <a>shadow root</a> by assigning a boolean <a href="#widl-ShadowRootInit-delegatesFocus">delegatesFocus</a> flag to be true in <a href="#idl-def-ShadowRootInit">ShadowRootInit</a> dictionary. If omitted, a <a>shadow host</a> does not delegate focus to its shadow root, and the shadow host itself can be focusable.</p>
+        <p>When a shadow host <var>HOST</var> delegates focus, user agent <strong>must</strong> behave as follows.
+          <ol>
+            <li>In <a>sequential focus navigation</a>, <var>HOST</var> itself will be skipped. See the next secition for the formal definition.</li>
+            <li>When <var>HOST</var> is focused by <code>focus()</code> method or <code>autofocus</code> attribute: The first <a>focusable area</a> in the tree order in <var>HOST</var>'s <a>shadow tree</a> gets focus.</li>
+            <li>When mouse is clicked on a node in <var>HOST</var>'s <a>shadow tree</a> and the node is not a <a>focusable area</a>: The first <a>focusable area</a> in the tree order in <var>HOST</var>'s <a>shadow tree</a> gets focus.</li>
+            <li>When any element in <var>HOST</var>'s <a>shadow tree</a> has focus, <code>:focus</code> pseudo-class applies to <var>HOST</var> in addition to the focused element itself.</li>
+	    <li>If <code>:focus</code> pseudo-class applies to <var>HOST</var>, and <var>HOST</var> is in a <a>shadow root</a> of another <a>shadow host</a> <var>HOST2</var> which also delegates focus, <code>:focus</code> pseudo-class applies to <var>HOST2</var> as well.</li>
+          </ol>
+        </p>
+      </section>
+
       <section>
         <h3>Sequential Focus Navigation</h3>
 
@@ -1567,6 +1581,8 @@ <h3><code>ShadowRootInit</code> dictionary</h3>
         <dl class="idl" title="dictionary ShadowRootInit">
           <dt>required ShadowRootMode mode</dt>
           <dd>Specifies the associated <a>mode</a> of <a>ShadowRoot</a></dd>
+          <dt>boolean delegatesFocus = false</dt>
+          <dd>Specifies whether shadow host delegates focus to its <a>ShadowRoot</a>. If omitted, the default value is false.</dd>
         </dl>
       </section>