In this paper, the authors illustrate the main functionalities and development methodologies of the ISYDES (Information System DEsign Support) system, a CASE tool for information system (IS) design and development. Such a tool is mainly composed of two software tools: the former allows the definition of the static structure of data, whereas the latter allows the whole specification of all functions, which constitute the dynamic part of an IS. This second step is very important in the design phase of an IS, as all the IS operations and processes are based on the specification of such functions. The proposed ISYDES tool adopts an object/oriented approach to the IS conceptual design; in particular it provides a way to specify the information processes that can be easily translated in the actual IS coded procedures.