The market for information technology products is rapidly changing from a manufactur er-driven market where new products were determined by the evolution of technology, to a user-driven market where users buy only products corresponding exactly to their needs and where competition is very strong. Confronted with this market situation, hardware and software producers are being obliged to adopt new strategies, and to make a large number of products available on the market in response to a variety of different needs. As a result of the multiplicity of choice available, the design of an office system which corresponds precisely to user needs is becoming an increasingly complex task. With exactly this in mind, the Commission, as early as 1985, invited submissions of projects aiming at the development of such adequate tools in its Call for Proposals for the ESPRIT Programme, in order to assist companies in the design of their office systems. This topic was recognised as being of strategic importance, considering the low level of penetration of Information Technology in European enterprises compared to the United States and Japan. Following this strategy, the project TODOS was selected and launched. This project has successfully developed tools and methods for the definition of the functional specifi cation of the office system, as well as the system architecture and user interface -results which can be of great interest for the IT community at large. 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.