为什么ItemsControl不使用我的ItemTemplate？

I am able to use an ItemTemplate within an ItemsControl to render items in a specific format. However, if one of the items within the ItemsControl happens to be, say, a TextBox, that TextBox is rendered rather than an instance of the ItemsTemplate. From what I can tell, this is true for any FrameworkElement. Is this intended behavior for an ItemsControl, or am I doing something incorrectly?I am able to use an ItemTemplate within an Item