Given my involvement with the Gerald R. Ford School of Public Policy, many have justifiably asked me to describe how a computational simulation could assist in the crafting of public policy. The Electricity Market Simulations run at Argonne National Lab represent a nice example. These are high level models run over six decision levels and include features such as a simulated bid market. Argonne has used this model to help the State of Illinois as well as several European countries regulate their markets for electricity.