The study results summarized here conclude that no simple sequential model can describe the development process; that a parallel model, adaptable to the needs of the particular project, is more realistic. This parallel model encompasses all of the disciplines involved in development: systems, hardware, software, reliability, testing, manufacturing, and so on. A project database is needed to accommodate all the many products of development and their complex relationships across all these disciplines. Such a model and database provide a reference for evaluating existing CASE tools and developing new ones. Existing CASE tools fall far short of meeting the needs of this model.