We describe a general purpose master-worker parallel computation Python module called PyMW. PyMW provides a unified interface to multiple computation environments including multicore processors, networked clusters and the Berkeley Open Infrastructure for Network Computing (BOINC) software platform. PyMW is intended to support rapid development, testing and deployment of large scale master-worker style computations. It is also designed to allow easy extension to other computing environments with little change in the master-worker program. We demonstrate the effectiveness and scalability of PyMW by performing several master-worker style parallel computations on a multicore machine, a networked cluster and a BOINC project.