Shortly … maybe are you collecting your controls in a StackPanel ?!??!
Well, it’s all due to that StackPanel … it has no limits, so those controls don’t know whether they are in-sight or out-of-sight.
Try a DockPanel instead, plus LastChildFill property is very helpfull.
More words about scrollbars, are here Use the Right Container for ListBox Scrolling .
Technorati Tags: WPF,StackPanel,Scrollbars.