Abstract. Domain-Specific Languages (DSL) offer many advantages over general languages, but their narrow scope makes them really effective only in very focused domains, for example Product Lines. The recent Model Driven Engineering (MDE) approach seeks to provide a technology to compose and combine models coming from different metamodels. Adapted to DSL, it means that it should be possible to compose “programs” written in different DSLs, which will enable the use of the DSL approach to build applications spanning different domains. The paper presents the Mélusine environment, where such a composition technology has been developed and experimented.