<Window x:Class="ControlStyles.Window1" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Title="ControlStyles" Height="300" Width="300"> <Window.Resources> <Style x:Key="StyleA"> <Setter Property="Control.FontSize" Value="20" /> <Setter Property="Control.FontWeight" Value="Bold" /> <Setter Property="Control.BorderThickness" Value="2" /> </Style> <Style x:Key="StyleB"> <Setter Property="Control.FontSize" Value="10" /> <Setter Property="Control.FontWeight" Value="Normal" /> <Setter Property="Control.BorderThickness" Value="1" /> </Style> </Window.Resources> <Grid> <Button Click="MyClickEvent" Style="{StaticResource StyleB}" VerticalAlignment="Top" HorizontalAlignment="Left" Grid.Column="0" Grid.ColumnSpan="1" Grid.Row="0" Grid.RowSpan="1" Margin="20" Width="75" Height="23" Name="btnGo">Go</Button> </Grid> </Window> //File:Window.xaml.cs using System; using System.Collections.Generic; using System.Text; using System.Windows; using System.Windows.Controls; using System.Windows.Data; using System.Windows.Documents; using System.Windows.Input; using System.Windows.Media; using System.Windows.Media.Imaging; using System.Windows.Shapes; namespace ControlStyles { public partial class Window1 : System.Windows.Window { public Window1() { InitializeComponent(); } private void MyClickEvent(object sender, RoutedEventArgs e) { btnGo.Style = (Style)FindResource("StyleA"); } } }