 <p>In a DataTemplate, the DataContext is set by default to the item that is represented by the DataTemplate (in that case, the Car object). If the EditCar command is on the main viewmodel (which also contains the MyCars collection), you need to explicitly set the Source of the Binding to that object. This would be (assuming that you are using the MVVM Light's ViewModelLocator and that your VM is named Main) {Binding Source={StaticResource Locator}, Path=Main.EditCar}</p> <p>Cheers, Laurent</p>