 <p>You can achieve this with a <code>DockPanel</code>:</p> <pre><code>&lt;DockPanel Width="300"&gt; &lt;TextBlock&gt;Left&lt;/TextBlock&gt; &lt;Button HorizontalAlignment="Right"&gt;Right&lt;/Button&gt; &lt;/DockPanel&gt; </code></pre> <p>The difference is that a <a href="http://msdn.microsoft.com/en-us/library/system.windows.controls.stackpanel.aspx" rel="nofollow noreferrer"><code>StackPanel</code> will arrange child elements into single line</a> (either vertical or horizontally) whereas a <a href="http://msdn.microsoft.com/en-us/library/system.windows.controls.dockpanel.aspx" rel="nofollow noreferrer"><code>DockPanel</code> defines an area where you can arrange child elements either horizontally or vertically, relative to each other</a> (the <code>Dock</code> property changes the position of an element relative to other elements within the same container. Alignment properties, such as <code>HorizontalAlignment</code>, change the position of an element relative to its parent element).</p>