The authors present Data Parallel Fortran (DPF), a set of extensions to Fortran aimed at programming scientific applications on a variety of parallel machines. DPF portrays a global name space to programmers and allows programs to be written in a clear, data-parallel style. DPF's model is based on the idea of having a single control thread that spans parallel virtual threads with arbitrary nesting, resuming at their completion into a single global state. It also provides explicit control of which subset of the global name space is strictly accessed by each virtual processor at different points in a program. This powerful mechanism makes it possible to write programs in which communication points are handled explicitly, but without making use of message passing code. Also, DPF offers some primitives that involve communication often encountered in parallel numerical and scientific applications. DPF semantics does not depend on any particular feature of the architecture, thus providing a reasonably high-level programming methodology. >