Set font size and font family for Button
<UserControl x:Class='SilverlightApplication3.MainPage' xmlns='http://schemas.microsoft.com/winfx/2006/xaml/presentation' xmlns:x='http://schemas.microsoft.com/winfx/2006/xaml' xmlns:d='http://schemas.microsoft.com/expression/blend/2008' xmlns:mc='http://schemas.openxmlformats.org/markup-compatibility/2006' mc:Ignorable='d' d:DesignWidth='640' d:DesignHeight='480'> <Canvas x:Name="LayoutRoot" Background="White"> <Button x:Name="loginButton" Content="Login" Canvas.Top="100" Canvas.Left="10" Width="80" FontFamily="Times New Roman" FontSize="12"/> </Canvas> </UserControl>