Society (as mandated by the Clean Air Act) requires that we protect our environment and minimize human exposure to harmful air pollutants with National Ambient Air Quality Standards(NAAQS). The authors also seek to minimize the economic costs of the necessary pollution control to meet the NAAQS targets. Air quality simulation models, and associated monitoring of air pollution provide information about current pollution levels. The models will require the handling of myriad of types and quality of information including input data such as emission inventories, boundary conditions, meteorological information, as well as solving numerous systems of equations that describe current understanding of the relevant and contributing processes. The EPA Models-3 system is currently being developed to satisfy these requirements and to provide a computational platform that will serve the air pollution community in their quest for the optimal air pollution control strategy.