 <p>There is no standard predefined parameter type which allows you to get the current user name as a Where parameter in markup (I guess you are talking about <code>User.Identity.Name</code>). Something simple like...</p> <pre><code>&lt;asp:Parameter Name="userName" DefaultValue='&lt;%# User.Identity.Name %&gt;' /&gt; </code></pre> <p>...doesn't work unfortunately since you cannot use data binding syntax in the parameter controls.</p> <p>But you can create <a href="http://www.4guysfromrolla.com/articles/110106-1.aspx" rel="nofollow noreferrer">custom parameters</a>. (On the second half of that page is a concrete example of a "user name parameter".)</p> <p>To your problem with the exception: I'm using the "it-Syntax" with navigation properties a lot in EntityDataSource and it looks more or less exactly like your example. Without seeing more of your model it's hard to tell what might cause the error. But generally, navigating through properties in EntityDataSource is supported and works.</p>