How to get a group of toggle buttons to act like radio buttons in WPF?

This is easiest way in my opinion.

<RadioButton Style="{StaticResource {x:Type ToggleButton}}" />

Enjoy! -- Pricksaw

The easiest way is to style a ListBox to use ToggleButtons for its ItemTemplate

<Style TargetType="{x:Type ListBox}">
    <Setter Property="ListBox.ItemTemplate">
        <Setter.Value>
            <DataTemplate>
                <ToggleButton Content="{Binding}" 
                              IsChecked="{Binding IsSelected, Mode=TwoWay, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type ListBoxItem}}}"
                />
            </DataTemplate>
        </Setter.Value>
    </Setter>
</Style>

Then you can use the SelectionMode property of the ListBox to handle SingleSelect vs MultiSelect.