This paper describes Method Registration, a technique for the creation of a highly extensible application environment. Although applicable to a variety of application domains, we are using Method Registration as the basis for a flexible imaging environment. Method Registration uses a simple declarative language to provide the application with knowledge about how to incorporate new functionality into the environment. The imaging environment we are developing will provide a visual programming based user interface to provide a very flexible mechanism for the end user to easily define complex image processing operations. Method Registration will provide the support to allow new image processing functionality to be added by developers without burdening them with interfacing to other layers of the application.