In view of the growing interest in and use of instructional simulations, a systematic approach to their development is described, including references to literature sources and to simulations already developed. Historical background, problems, and advantages of the use of instructional simulation are covered, and numerous definitions of often-used terms are included. The document concludes with a complete listing of the instructional simulations now in various stages of development at the CAI Center. Graphs are used to give overall views of the current standing of each simulation, and of the range of target populations suggested for each. (Author)