This thesis presents high-performance, portable and efficient techniques for communication between parallel programs written using the Message Passing Inteface (MPI) libraries and High Performance Fortran (HPF). Our techniques, communication with UNIX sockets, communication with MPI and communication using shared memory, have been tested and run on a distributed memory machine (IBM SP2), shared memory machines (IIP Exemplar, SGI Origin 2000) and the Globus metacomputing toolkit. The characteristics of the techniques on each platform are discussed. We believe our techniques will be useful for integrating existing MPI and HPF codes. In addition, MPI-HPF communication will be useful, where a mixture of data and task parallelism is desired. This is because MPI is popularly used for implementing task parallelism and HPF is an effective language for implementin data parallel applications. The behavior and integration of application codes iwth our communication techniques is also presented in this thesis.