Abstract. Software systems today need to dynamically self-adapt against dynamic requirement changes. In this paper we describe RAMSES a reflective middleware whose aim consists of consistently evolving software systems against runtime changes. This middleware provides the ability to change both structure and behavior for the base-level system at run-time by using its design information. The meta-level is composed of cooperating objects, and has been specified by using a design pattern language. The base objects are controlled by meta-objects that drive their evolution. The essence of RAMSES is the ability of extracting the design data from the base application, and of constraining the dynamic evolution to stable and consistent systems.