The WriteValue method is not called in the Windows Forms Property Editors because they support Binding (see System.Windows.Forms.Binding in MSDN). However, the PropertyEditor.ValueStoring, PropertyEditor.ControlValueChanged and PropertyEditor.ValueStored events are additionally raised. So, when implementing a descendant of the PropertyEditor class that supports binding, call the OnValueStoring and OnValueStored methods where required, so that you can subscribe the corresponding events. If you implement a Property Editor and do not use Binding, override the WriteValueCore method if you need to perform additional actions, except setting the PropertyValue to the ControlValue. In this instance, you do not have to be concerned with raising the corresponding events.