An architecture for customizable applications includes an application object and a customization object. The application object has internal logic that performs a set of fixed or predetermined actions, and a public object model. The public object model includes a set of public methods that are invocable on the application object, and a set of event source which are methods that can be implemented by a programmer and are called by the internal logic of the application object. By implementing methods invocable by the event sources, it is possible to extend and customize the functionality of the application object. The customizations are stored in a customization database for retrieval during the dynamic operation of the application object. Each customization may be identified by a “moniker,” which is a string having a hierarchical format. The moniker is derived partly from fixed data known to the application object, and partly from environmental data that is ascertained by the application object at run time.