This paper presents a hierarchical modeling method that can be used to simulate a Flexible Manufacturing System (FMS) at all levels of detail. The method was developed specifically to aid the software development needed for the hierarchy of computers that are present in an FMS. The method was developed by modeling an existing FMS. The models developed of the existing FMS are described in detail to provide an example of how to model other FMSs. The basic building blocks needed for designing other FMSs with this modeling method are provided. The models were written in the SIMAN simulation language. SIMAN was found to be an easy language to use for the hierarchical modeling of FMSs. / M.S.