public ProjectViewModel() { Tasks = new ReactiveList <TaskViewModel>(); Tasks.Add(new TaskViewModel { Title = "Add new tasks command" }); Tasks.Add(new TaskViewModel { Title = "Add delete task command" }); Tasks.Add(new TaskViewModel { Title = "Allow reorder of tasks" }); AddTask = this.WhenAny(x => x.NewTaskTitle, x => !String.IsNullOrWhiteSpace(x.Value)).ToCommand(); AddTask .Select(_ => new TaskViewModel { Title = NewTaskTitle }) .Subscribe(x => { Tasks.Add(x); NewTaskTitle = String.Empty; }); }