I'm developing MVVM application. I bind the DataGrid ItemsSource to a ObservableCollection in the ViewModel code. Every user control (eg. TextBox, Label, etc) in the UI except the DataGrid works fine. When the PropertyChanged event is fired, the value is displayed correctly. But not in the DataGrid, I use TwoWay mode, but it seems that the DataGrid never refresh itself. The DataGrid content is refreshed only when I try to sort any DataGrid column.