The purpose of this program is to represent large scale global processes. It is the third stage of development in a series of man-computer simulations of international relations. The first model in the series was called the Inter-Nation Simulation and was developed by Harold Gueztkow and his colleagues at Northwestern University. The second stage, International Processes Simulation (IPS) was developed by Paul Smoker at Lancaster and Northwestern Universities. Global Systems Simulation incorporates improved versions of IPS and adds a limits of growth component developed at the University of British Columbia.