Copyright @ 2008 Springer-VerlagThis chapter presents a sample of empirical studies of Open Source Software (OSS) evolution. According to these studies, the classical results from the studies of proprietary software evoltion, such as Lehman’s laws of software evolution, might need to be revised, if not fully, at least in part, to account for the OSS observations. The book chapter also summarises what appears to be the empirical
status of each of Lehman’s laws with respect to OSS and highlights the threads to
validity that frequently emerge in these empirical studies. The chapter also discusses
related topics for further research