I'd like to keep my concrete classes separate from my views. Without using strongly typed views, I'm fine. I just use a big parameter list in the controller method signatures and then use my service layer factory methods to create my concrete objects. This is actually just fine with me, but it got me thinking and after a little playing, I realized it was literally impossible for a controller method to accept an interface as a method parameter - because it has no way of instantiating it. Can't create a strongly-typed view using an interface through the IDE either (which makes sense actually). So my question. Is there some way to tell the controller how to instantiate the interface parameter using my service layer factory methods? I'd like to convert from: [Authorize] [AcceptVerbs(HttpVerbs.Post)] [UrlRoute(Path = "Application/Edit/{id}")] public ActionResult Edit(String id, String TypeCode, String TimeCode, String[] SelectedSchoolSystems, String PositionChoice1, String PositionChoice2, String PositionChoice3, String Reason, String LocationPreference, String AvailableDate, String RecipientsNotSelected, String RecipientsSelected) { //New blank app IApplication _application = ApplicationService.GetById(id); to something like [Authorize] [AcceptVerbs(HttpVerbs.Post)] [UrlRoute(Path = "Application/Edit/{id}")] public ActionResult Edit(String id, IApplication app) { //Don't need to do this anymore //IApplication _application = ApplicationService.GetById(id);