In September of 1994 a workshop was held at Argonne National Laboratory on implementation issues for MPI. MPI is a standard message-passing library interface developed during 1993 and 1994 by the MPI Forum, a broadly based group of parallel computing vendors, parallel library writers, and application, scientists. The purpose of the Workshop was to gather together those vendors and others actively engaged in implementing the Standard in order to discuss issues raised by the implementation process. A secondary aim was to explore the possibility of pooling some efforts in order to speed and ease the adoption of MPI. we briefly describe the implementation efforts that were presented at the Workshop, summarize the discussions that took place on the Standard itself and implementation issues, and offer some general conclusions about the state of the MPI implementation effort worldwide.