There are several Calendar classes in the Framework. If you're saying that it is na abstract class then presumably you're talking about the Globalization.Calendar class. Have you actually read about that class and the classes that inherit it? It has nothing to do with controls. Each derived class provides information about a type of calendar and they include GregorianCalendar, JulianCalendar, KoreanCalendar, etc. If you want to create a calendar application like Outlook or something then you're looking in the wrong place. Like any application it will take many objects interacting to get the job done. You may be able to use an instance of a derived Calendar class to do some of the calculations required within your app, but it will take a lot more than that.