 <p>As you're using GroupBy extension method you're getting list of grouped items where each group is enumerable of elements with same OfferId.That's why you have <code>'System.Collections.Generic.List&lt;System.Linq.IGrouping&lt;long,myDAL.viewOffers&gt;&gt;'</code> as a result of your operation. Look into <a href="http://msdn.microsoft.com/en-us/library/bb344977.aspx" rel="nofollow">IGouping</a> documentation.</p>