As reported to Microsoft Connect: Silverlight Grid/StackPanel/Canvas ActualHeight and AcutalWidth is 0 http://connect.microsoft.com/VisualStudio/feedback/details/522231/silverlight-grid-stackpanel-canvas-actualheight-and-acutalwidth-is-0 and as described in the API document: FrameworkElement.ActualHeight Property http://msdn.microsoft.com/en-us/library/system.windows.frameworkelement.actualheight%