Create a ListBoxItem, set font, content, add the ListBoxItem to the ListBox
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Title="WPF" Height="300" Width="300"> List Item 1 List Item 2 List Item 3
//File:Window.xaml.cs using System.Windows; using System.Windows.Controls; using System.Windows.Media; namespace WpfApplication1 { public partial class Window1 : Window { public Window1() { InitializeComponent(); } private void btnAddListItem_Click(object sender, RoutedEventArgs e) { if (textBox.Text.Length == 0) { MessageBox.Show("Enter text to add to the list.", Title); } else { ListBoxItem item = new ListBoxItem(); item.Content = textBox.Text; item.IsSelected = true; item.HorizontalAlignment = HorizontalAlignment.Center; item.FontWeight = FontWeights.Bold; item.FontFamily = new FontFamily("Tahoma"); listBox1.Items.Add(item); textBox.Clear(); textBox.Focus(); } } private void btnDeleteListItem_Click(object sender, RoutedEventArgs e) { if (listBox1.SelectedItems.Count == 0) { MessageBox.Show("Select list items to delete.", Title); } else { while (listBox1.SelectedItems.Count > 0) { listBox1.Items.Remove(listBox1.SelectedItems[0]); } } } private void btnSelectAll_Click(object sender, RoutedEventArgs e) { listBox1.SelectAll(); } } }