Dear Boosters, I am just going through the learning curve for Boost.MPI. My underlying target platform is MPICH2 on Windows XP/Vista. Given I am taking baby-steps I would like run the regression tests to check my install. Mpirun doesn't exist in my install - mpiexec is required instead. The docs and mpi.jam comments say "The (optional) fourth argument configures Boost.MPI for running regression tests. These parameters specify the executable used to launch jobs (default: "mpirun") followed by any necessary arguments to this to run tests and tell the program to expect the number of processors to follow (default: "-np")." I'm no jam expert, but that suggests that my user-config.jam should change to using mpi : : <find-shared-library>cxx <find-shared-library>mpi <library-path>C:/MPICH2/lib <include>C:/MPICH2/include : : mpiexec -n ; where the " : : mpiexec -n " is the new part. However this results in a slew of jam errors. I am able to run the regression tests by hacking mpi.jam to change the defaults, however I'd prefer to know the correct syntax in user-config.jam please. Thanks in advance for any help, Pete Bartlett