We have recently introduced Opus, a set of Fortran language extensions that provide shared data abstractions (SDAs) as a mechanism for communication and synchronization among coarse-grain data parallel tasks. In this paper, we discuss the design and implementation issues of the runtime system necessary to support SDAs, and outline the underlying requzrements for such a runtzme system. W e explore the feasibility of this approach by implementing a prototype of the runtrme system. We give prelimznary results of the prototype on the Intel Paragon, outline the current status of the project, and discuss future plans.