 <p>You need to have a property to bind the selected items to. A multiple <code>&lt;Select&gt;</code> binds to, and post back an array of value types.</p> <pre><code>public class MyViewModel { public int[] SelectedContacts { get; set; } public List&lt;Contact&gt; AvailableContacts { get; set; } } </code></pre> <p>View</p> <pre><code>@Html.ListBoxFor(m =&gt; m.SelectedContacts, new SelectList(Model.AvailableContacts, "ExternalUserID", "PublicName"), new { @class = "form-control", size = "15" }) </code></pre>