private void listBox_Loaded(object sender, RoutedEventArgs e) { CalendarReader cl = new CalendarReader(); cl.GoogleMain(); events = new ObservableCollection <string>(cl.gcevents); dates = new ObservableCollection <string>(cl.dates); foreach (string f in events) { foreach (string d in dates) { listBox.Items.Add((f.ToString() + " " + (d) + "\n")); } } }