If you find yourself applying those 2 roles often you can wrap them in their own Authorize. This is really an extension of the accepted answer.
using System.Web.Mvc;
public class AuthorizeAdminOrMember : AuthorizeAttribute
{
public AuthorizeAdminOrMember()
{
Roles = "members, admin";
}
}
And then apply your new authorize to the Action. I think this looks cleaner and reads easily.
public class MyController : Controller
{
[AuthorizeAdminOrMember]
public ActionResult MyAction()
{
return null;
}
}