 <p>According to the spec the <code>&lt;p&gt;</code> element cannot contain <code>"block-level elements (including P itself)"</code>. My guess is Chrome is just trying to be helpful here.</p> <p>Source: <a href="http://www.w3.org/TR/html401/struct/text.html#h-9.3.1" rel="nofollow">http://www.w3.org/TR/html401/struct/text.html#h-9.3.1</a></p>