This paper describes an effort in which the design of an entire missile system consisting of a ramjet powered sustainer and an associated solid rocket booster is considered. The design process is controlled by a genetic algorithm optimizer which directs and controls other system performance prediction codes. The optimizer used in the present process is the IMPROVE © code, a genetic algorithm (GA) with many advanced features including a pareto option and nicheing. The paper contains limited discussion of the methodology and shows results for several design scenarios. The results are to be interpreted as a “proof of concept” effort and are not directed toward a specific design problem.