The development of the AT&T System 75 office communication system required the coordinated effort of many designers working on a large number of individual components of the product. This article describes the project environment and methods created to accomplish this task. Emphasis is placed on the uncommon aspects of the project: the hierarchy of product specification documents that provided great flexibility in design decisions; the concept of a feature engineer that allowed for the vertical development of a feature by one person from feature specification to software code; the baselining and change control procedures that kept decision making at the lowest possible level; the tracking of progress so that prompt corrective action could be taken as problems arose; and the high reliance on electronic documentation and communication. I. THE DEVELOPMENT PROCESS OverviewThe development of the AT&T System 75 office communication system spanned almost three years from product definition to introduction. The process consisted of a sequence of steps including requirements generation, external and internal design specification, imple-