This thesis presents the development of an interactive graphics interface for MECSYN, a planar mechanism synthesis program. The purpose of this work is to produce a dynamic graphics interface, independent of a graphics device and providing a high level of user interaction. To achieve this, the proposed three-dimensional graphics standard PHIGS (Programmers Hierarchical Interactive Graphics System) is used for graphics support software. An overview of the synthesis theory is presented. The program structure is described and presented along with a listing of the graphics and interface routines of the program to aid in future development of the program (synthesis routines are not included). Several examples illustrating the features and use of the program have been included. / Master of Science