A study was performed to develop an interactive plane frame analysis program. The program was designed to run on Unix-based workstations and to be independent of the hardware platform. This was achieved by selecting the XWindow system as the underlying graphical user-interface. An event-driven, window-based program was developed using the XWindow Toolkit. The entire program was written in the C programming language. The program consists of two parts: a preprocessor and a processor. The preprocessor employs pull-down menus and pop-up dialog boxes and provides a convenient way of creating and modifying structural models. The processor performs linear elastic analysis of plane frame structures based on the matrix displacement method. The processor computes joint displacements, support reactions and local member-end forces of the structure. It also handles internal hinges, joint loads, member loads, prescribed displacements, multiple load cases and load combinations. Other features include automatic mesh generation for orthogonal frames, automatic computation of self-weight and specification of output options. To verify the accuracy of the program, analysis results from the program were compared with results obtained from a commercial structural analysis program. A comparison of joint displacements, support reactions and member-end forces indicate that the difference in the values obtained from the two programs is less than two percent and that the program provides accurate analysis results. / Master of Science