Book excerpt: Flexible manufacturing systems are complex production systems with considerable high investment costs. This book intends to show the reader how the design of such a system can be optimized. Thereby it addresses the academic world in management science and industrial engineering as well as system planners in industry. First the design problems are analysed in detail and a planning concept is presented. Afterwards possible tools for the design process are described, as there are: mathematical programming, queueing networks, computer simulation, perturbation analysis, petri nets, group technology, and knowledge based systems. The major part of the book, however, concerns the description of existing optimization models based on mathematical programming. Each model is explained and discussed in detail and for new models, developed by the author, numerical examples are given. Finally some distinct guidelines are presented which help the system planners to select the appropriate model for their planning problems.