“Crimesim” is a new computer simulation model that can be adapted for use in any criminal justice system or agency without extensive knowledge of computers or computer languages. The model is designed to be used by researchers, planners, and decision makers. Crimesim models a system by allowing one to determine which of available alternatives will provide the greatest benefit, in terms of stated priorities and cost effectiveness. The model can be used as a tool in decision making by helping the user to organize and analyze information and assess possible alternatives. © 1979, Sage Publications. All rights reserved.