Specifying a Stretch and alignment
<Page xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" HorizontalAlignment="Stretch" VerticalAlignment="Stretch"> <Rectangle> <Rectangle.Fill> <ImageBrush ImageSource="c:\image.jpg" Stretch="UniformToFill" AlignmentX="Left" AlignmentY="Bottom" /> </Rectangle.Fill> </Rectangle> </Page>