Two models in one view in ASP MVC 3

To use the tuple you need to do the following, in the view change the model to:

@model Tuple<Person,Order>

to use @html methods you need to do the following i.e:

@Html.DisplayNameFor(tuple => tuple.Item1.PersonId)

or

@Html.ActionLink("Edit", "Edit", new { id=Model.Item1.Id }) |

Item1 indicates the first parameter passed to the Tuple method and you can use Item2 to access the second model and so on.

in your controller you need to create a variable of type Tuple and then pass it to the view:

    public ActionResult Details(int id = 0)
    {
        Person person = db.Persons.Find(id);
        if (person == null)
        {
            return HttpNotFound();
        }
        var tuple = new Tuple<Person, Order>(person,new Order());

        return View(tuple);
    }

Another example : Multiple models in a view

Create a parent view model that contains both models.

public class MainPageModel{
    public Model1 Model1{get; set;}
    public Model2 Model2{get; set;}
}

This way you can add additional models at a later date with very minimum effort.

Another option which doesn't have the need to create a custom Model is to use a Tuple<>.

@model Tuple<Person,Order>

It's not as clean as creating a new class which contains both, as per Andi's answer, but it is viable.