The increasing complexity of systems has enhanced the use of simulation as a decision-support tool. Often, simulation is the only scientific methodology available to practitioners for the analysis of complex systems. However, only a small fraction of the practical benefits of simulation modeling and analysis have reached the potentially large user community because of the relatively high requirement of time, effort and cost needed to build and successfully use simulation models. We describe a model-based approach that seeks to address these problems via the implementation of MODELSIM, a comprehensive modeling and analysis architecture that includes: application of the IDEF3 and IDEF5 methods for simulation modeling and analysis specification; automatic generation of executable component-based simulations from IDEF-based descriptive models; and reusable libraries of modeling components to facilitate rapid configuration of models as needed over extended periods of time.