Gardens integrates a programming language and system to support parallel computation over a network of workstations. Our goal is to develop extensions to Gardens allowing it to efficiently support clusters of SMP machines under a uniform programming model. Such support requires the implementation of high-performance shared memory message passing primitives as well as changes to the existing model invariants and the Gardens runtime system itself. The new communication primitives have demonstrated a minimum latency of 2.0 microseconds and can maintain a maximum bandwidth of approximately 194 MB/s on our test system. The NAS benchmarks, EP and CG have also demonstrated significant performance increases when parallelized by Gardens. The major contribution of this work is a system that efficiently supports multiprocessor computers in a network of workstations with a uniform programming model. Such a system promises to greatly simplify the task of developing high-performance parallel applications to run on CLUMPS.