Implementing realistic scientific applications on parallel platforms requires a high-level, problem-adequate and flexible programming environment. The hybrid system PRO-MOTER pursues a two-level approach allowing easy and flexible programming at both language and library levels. The core concept of PROMOTER'S language model is its highly abstract and unijied concept of data and communication structures. The paper briefly addresses the programming model, but focuses on implementation aspects of the compiler and runtime system. Finally, pe$ormance results are given, evaluating the eficiency of the PROMOTER system.