Public Property LayerItemsMode As Legend.Mode

public Legend.Mode LayerItemsMode {get; set;}

<Grid x:Name="LayoutRoot" >
  
  <!-- Add a Map Control. -->
  <esri:Map Background="White" HorizontalAlignment="Left" Margin="12,188,0,0" Name="Map1" 
            VerticalAlignment="Top" Height="350" Width="350" >
    
    <!-- Add an ArcGISDynamicMapServiceLayer. -->
    <esri:ArcGISDynamicMapServiceLayer
      Url="http://sampleserver1.arcgisonline.com/ArcGIS/rest/services/Demographics/ESRI_Census_USA/MapServer"/>
      
  </esri:Map>
  
  <!--
  Add a Legend Control to the application. The Legend is bound to Map1. Set the ShowOnlyVisibleLayers=False 
  to display all available sub-Layers and group-Layers from the ArcGISDynamicMapServiceLayer in the Legend 
  even though some scale dependency thresholds have been set in the map service. 
  -->
  <esri:Legend Name="Legend1" HorizontalAlignment="Left" VerticalAlignment="Top" 
               Margin="368,188,0,0" Width="350" Height="350" 
               Map="{Binding ElementName=Map1}"
               ShowOnlyVisibleLayers="False"/>
    
  <!--
  Add two Buttons; one to set the Legend.LayerItemsMode = Tree and the other to set the 
  Legend.LayerItemsMode = False. The Click Events for each button have code-behind functionality.
  -->
  <Button Content="LayerItemsMode: Tree" Height="23" HorizontalAlignment="Left" Margin="12,159,0,0" 
          Name="Button_LayerItemsMode_Tree" VerticalAlignment="Top" Width="350" 
          Click="Button_LayerItemsMode_Tree_Click"/>
  <Button Content="LayerItemsMode: Flat" Height="23" HorizontalAlignment="Left" Margin="368,159,0,0" 
          Name="Button2" VerticalAlignment="Top" Width="350" 
          Click="Button_LayerItemsMode_Flat_Click"/>
  
  <!-- Provide the instructions on how to use the sample code. -->
  <TextBlock Height="95" HorizontalAlignment="Left" Name="TextBlock1" VerticalAlignment="Top" Width="756" 
         TextWrapping="Wrap" Margin="12,12,0,0" 
         Text="Click the two buttons 'LayerItemsMode: Tree' and 'LayerItemsMode: Flat' to see how the 
             Legend has different appearances. The Legend_Refreshed Event is overridden to collapse
             the individual LegendItems (i.e. the map symbol images) so that differences in the 
             LayerItemsMode settings can more readily be seen." />
</Grid>

// NOTE: Don’t forget to insert the following event handler wireups at the end of the 'InitializeComponent' 
// method for forms, 'Page_Init' for web pages, or into a constructor for other classes:
Legend1.Refreshed += new ESRI.ArcGIS.Client.Toolkit.Legend.RefreshedEventHandler(Legend1_Refreshed);
  
private void Button_LayerItemsMode_Tree_Click(object sender, System.Windows.RoutedEventArgs e)
{
  Legend1.LayerItemsMode = ESRI.ArcGIS.Client.Toolkit.Legend.Mode.Tree;
}
            
private void Button_LayerItemsMode_Flat_Click(object sender, System.Windows.RoutedEventArgs e)
{
  Legend1.LayerItemsMode = ESRI.ArcGIS.Client.Toolkit.Legend.Mode.Flat;
}
            
private void Legend1_Refreshed(object sender, ESRI.ArcGIS.Client.Toolkit.Legend.RefreshedEventArgs e)
{
  // The rendering of the Legend Control happens asynchronously. Use the Legend.Refreshed Event to demonstrate
  // custom changes in what the Legend displays. This function overrides the default behavior of how LegendItems
  // are displayed. Instead of showing each LegendItem (i.e. the map symbol images) individually, only the 
  // Layer/sub-Layer/group-Layer leaves in the Legend are displayed to emphasize how the Legend.LayerItemsMode
  // works.
  
  // Close all of the LegendItem leaves (i.e. the lowest level of leaves) 
  IEnumerable<ESRI.ArcGIS.Client.Toolkit.Primitives.LegendItemViewModel> theIEnumerable = Legend1.LayerItemsSource;
  foreach (ESRI.ArcGIS.Client.Toolkit.Primitives.LegendItemViewModel theLegendItemViewModel in theIEnumerable)
  {
    theLegendItemViewModel.IsExpanded = false;
  }
  
  // Expand the LayerItem leaves (i.e. the Layer/sub-Layer/group-Layer leaves)
  Collections.ObjectModel.ObservableCollection<ESRI.ArcGIS.Client.Toolkit.Primitives.LayerItemViewModel> theObservableCollection = Legend1.LayerItems;
  foreach (ESRI.ArcGIS.Client.Toolkit.Primitives.LayerItemViewModel theLayerItemViewModel in theObservableCollection)
  {
    theLayerItemViewModel.IsExpanded = true; //False
  }
}

Private Sub Button_LayerItemsMode_Tree_Click(ByVal sender As System.Object, ByVal e As System.Windows.RoutedEventArgs)
  Legend1.LayerItemsMode = ESRI.ArcGIS.Client.Toolkit.Legend.Mode.Tree
End Sub
            
Private Sub Button_LayerItemsMode_Flat_Click(ByVal sender As System.Object, ByVal e As System.Windows.RoutedEventArgs)
  Legend1.LayerItemsMode = ESRI.ArcGIS.Client.Toolkit.Legend.Mode.Flat
End Sub
            
Private Sub Legend1_Refreshed(ByVal sender As Object, ByVal e As ESRI.ArcGIS.Client.Toolkit.Legend.RefreshedEventArgs) Handles Legend1.Refreshed
  
  ' The rendering of the Legend Control happens asynchronously. Use the Legend.Refreshed Event to demonstrate
  ' custom changes in what the Legend displays. This function overrides the default behavior of how LegendItems
  ' are displayed. Instead of showing each LegendItem (i.e. the map symbol images) individually, only the 
  ' Layer/sub-Layer/group-Layer leaves in the Legend are displayed to emphasize how the Legend.LayerItemsMode
  ' works.
  
  ' Close all of the LegendItem leaves (i.e. the lowest level of leaves) 
  Dim theIEnumerable As IEnumerable(Of ESRI.ArcGIS.Client.Toolkit.Primitives.LegendItemViewModel) = Legend1.LayerItemsSource
  For Each theLegendItemViewModel As ESRI.ArcGIS.Client.Toolkit.Primitives.LegendItemViewModel In theIEnumerable
    theLegendItemViewModel.IsExpanded = False
  Next
            
  ' Expand the LayerItem leaves (i.e. the Layer/sub-Layer/group-Layer leaves)
  Dim theObservableCollection As Collections.ObjectModel.ObservableCollection(Of ESRI.ArcGIS.Client.Toolkit.Primitives.LayerItemViewModel) = Legend1.LayerItems
  For Each theLayerItemViewModel As ESRI.ArcGIS.Client.Toolkit.Primitives.LayerItemViewModel In theObservableCollection
    theLayerItemViewModel.IsExpanded = True 'False
  Next
  
End Sub