Extreme Programming (XP) is an agile software development methodology composed of several practices that purportedly yield high quality and high customer satisfaction. However, there has been little formal investigation of these claims. We conduct empirical, industrial case studies to evaluate XP. Results from two case studies are presented. Categories and Subject Descriptors K.6.3 [Management of Computing and Information Systems]: Software Management — software process; and D.2.9 [Software Engineering]: Management — life cycle, programming teams General Terms Management, Measurement, Experimentation, Human Factors Keywords Agile software development, extreme programming, case studies