The TODOS methodology and design support environment for office information systems development are presented in this book. In TODOS, a method for the definition of an office system is proposed, and tools support the developer in the different design phases in making design choices, analyzing results, and presenting these design results to final users of the office systems. The main ideas underlying the TODOS approach are the goal of avoiding unnecessary reimplementation of hardware and software components available on the market, and the use of computer based design support tools to achieve this goal. Data and knowledge bases are used in TODOS to store information about available components and about design choices. A prototyping tool is used to present the office system to the users before its actual realization, to obtain users' evaluation. The book is mainly oriented to professionals looking for a method for office system development. It may also be valuable for office system managers interested in exploring possibilities of developing office information systems in their organizations. Moreover, it offers material for study in the academic world: researchers in the field can extend the approach defining new advanced design support tools; students can examine the state of the art in office system development support tools, and study office design support environments.