With the recent emergence of agile software development technologies like XP, many organizations, small and large, have adopted XP or a subset of its practices. This talk describes the empirical evaluation of the XP development process in terms of industrial case studies performed at IBM, Sabre and Tekelec. These case studies involve measurement of various product and process measures to compare the XP process and also discusses the obstacles that were encountered during the case studies. This talk also provides a brief comparative introduction between XP-1 and the recent XP-2 processes.