Early research studies on open source software development often betrayed a mild surprise that loosely coordinated networks of volunteers could manage the design and implementation of highly comple software products. In the past few years, a wider research community has become increasingly aware of the tremendous contribution that open source development is making to the software industry, business and society in general. Software engineering researchers are exploring OSS specifically with respect to development tools and methodologies, while organizational scientists and economists are keen on understanding how open sources have brought large communities of people to help each other effectively. This book is an important step in the direction of a fuller understanding of the OSS phenomenon. It collects the proceedings of the Second International Conference on Open Software held in Como, Italy, from June 8th to June 10th, 2006. OSS 2006 was the foundation conference of the IFIP TC 2 WG 2. 13 on Open Source Software, and attracted many researchers from all over the world interested in how OSS is produced, in its huge innovation potential in many different application fields and in OSS innovative business models. The 20 full papers of this volume were selected via a rigourous refereeing process among more than 100 submissions; 12 additional submissions, in view of their interest, were selected for publication in a more concise form.