Discussed is the design, implementation and use of a graPHIGS (IBM PHIGS) based sub-system that provides for shading of graphical models using the Phong shading technique. The ISO standard for 3D graphics, PHIGS, provides for wireframe display and manipulation of graphics data. PHIGS + implementations, while providing this capability, will not be widely available for some time. This capability will provide a generally useful extension to PHIGS for use by PHIGS based applications. The software provides the applications programmer with a graPHIGS based instruction set which acts as a superset to the current graPHIGS calls. Using the provided functions the user can quickly do hidden surface elimination and Phong rendering of 3-D models in 3-D views. The program contains approximately 15,000 lines of C code and uses graPHIGS inquiries and calls for information retrieval and data structure maintenance. / Master of Science