Beginning with definitions of "simulation" (a methodology for testing alternative decisions under hypothetical conditions), this paper focuses on the use of simulation as an instructional method, pointing out the relationships and differences between role playing, games, and simulation. The term "simulation games" is explored with an analysis of six dimensions of simulated environments: reality and fidelity; complexity of decisions; curriculum content; source of model, simulation, and game; replicability; and evaluation. After a brief discussion of computer-based simulation games, the advantages and disadvantages of simulation as a method of instruction are listed. Included are a glossary of terms related to simulation (analog, game theory, heuristic, iterative, model, role-playing, simulation, and system) and a 28-item selected, annotated bibliography. (JS)