This text contains the proceedings of a workshop on software develoDment tools, held at Pingree Park, Colorado in May, 1979. The workshop, for which we were co-chair men, was primarily, but not exclusively, concerned with a variety of tools supporting pre-implementation phases of software development. The workshop brought together researchers and practitioners from industrial, governmental, and academic sectors to compare and assess current work and to set some directions for future work in this emerging technical area. The fifty participants represented research and development efforts in software tools within the United States, Canada, France, Great Britain, and Japan. (A list of participants appears at the end of the text. ) Sponsorship was provided by the National Aeronautics and Space Administration, the National Bureau of Standards, the National Science Foundation, and Digital Equipment Corporation. The conference consisted of seven formal sessions and numerous organized and impromptu discussions. Each session (except the last) included invited papers, prepared remarks by discussants, and an open discussion."