Secure group communication in mobile ad hoc networks is often dynamic and impromptu, and thus requires efficient and automated secure group management and seamless combination of secure groups with distributed applications running upon them. Existing approaches to secure group communication cannot satisfy these requirements. In this paper, an automated secure group management approach is presented. Based on this approach, a middleware service for secure group communication is developed to facilitate development and execution of distributed applications using secure group communication in mobile ad hoc networks. This middleware service is implemented in a context sensitive middleware RCSM.