This paper describes the DiKe model-based diagnosis framework, which incorporates multiple diagnosis engines, multiple user-level system description languages, a theorem prover, and a graphical user interface to provide an integrated toolset for the development of model-based diagnosis applications. The framework has been used for representing a number of application domains. We present the AD2L language, the main user language for the system geared towards use by non-specialists, and discuss use of DiKe in various domains.