This paper describes a parallel implementation of the direct simulation Monte Carlo method. Runtime library support is used for scheduling and execution of communication between nodes, and domain decomposition is performed dynamically to maintain a favorable load balance. Performance tests are conducted using the code to evaluate various remapping and remappinginterval policies, and it is shown that a one-dimensional chain-partitioning method works best for the problems considered. The parallel code is then used to simulate the Mach 20 nitrogen JYow over a finite-thickness fiat plate. It will be shown that the parallel algorithm produces results which are very similar to previous DSMC results, despite the increased resolution available. However, it yields significantly faster execution times than the scalar code, as well as very good load-balance and scalability characteristics. (Also cross-referenced as UMIACS-TR-95-25)