Abstract. A wide variety of techniques and approaches are needed to understand and improve software development processes. The critical research problem is supporting the move from completely informal process descriptions to a form that includes parts that are at least machine processable. We discuss a series of engineering experiments on process visualization and analysis using simple process interface descriptions. This work grew out of two needs: the need to understand a process's internal structure and the need to understand and improve the process system's architecture. We discuss the various approaches we have taken to understand processes from these two standpoints: we report on the di erent forms of visualization we have used, both for processes in the small as well as processes in the large, and their resulting bene ts; we delineate the various forms of analysis and report how they have played a seminal role in process improvement by providing the quantitative basis of both process understanding and process improvement e orts.