<UserControl x:Class="SilverlightApplication3___hierarchical.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"
             xmlns:sdk="http://schemas.microsoft.com/winfx/2006/xaml/presentation/sdk"
             mc:Ignorable="d"
             d:DesignHeight="300"
             d:DesignWidth="400">

    <Grid x:Name="LayoutRoot"
          Background="White">
        <sdk:TreeView x:Name="treeView">
            <sdk:TreeView.ItemTemplate>
                <sdk:HierarchicalDataTemplate ItemsSource="{Binding Items}">
                    <TextBlock Text="{Binding Name}" />
                </sdk:HierarchicalDataTemplate>
            </sdk:TreeView.ItemTemplate>
        </sdk:TreeView>
    </Grid>
</UserControl>

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;

namespace SilverlightApplication3___hierarchical {
    public partial class MainPage : UserControl {
        public MainPage() {
            InitializeComponent();

            this.treeView.ItemsSource = new List<DataItem> { 
                new DataItem {Name = "1", Items = new List<DataItem>{
                    new DataItem {Name = "1.1", Items = new List<DataItem> {
                        new DataItem {Name = "1.1.1"}
                    }
                }},
            }};
        }
    }

    public class DataItem {
        public string Name { get; set; }
        public IEnumerable<DataItem> Items { get; set; }

        public DataItem() {
            this.Items = new List<DataItem>();
        }
    }
}