The UltraCalendarCombo control does not support masking. UltraDateTimeEditor does, although it displays a .NET MonthCalendar control in the dropdown portion. You can use the Infragistics framework to "roll your own" control that does both these things, by adding a DropDownEditorButton to an UltraMaskedEditor's EditorButtons collection, then assigning an UltraMonthViewMulti control to the DropDownEditorButton's Control property. There is some additional coding necessary to move the edited value between the masked edit control and the dropdown, but not that much.