This thesis is about open source. The open source software (OSS) has drawn the attention of many researchers from various fields since the turn of the century (von Krogh et Spaeth, 2007: 236). According to the Free Software Foundation a piece of software is considered as free software if its users' have four freedoms: to run, to copy, to distribute and to improve the software (Free Software Foundation, 2007). This research gives relevant answers to theoretical and practical questions which were not investigated, either in some cases only partially or insufficiently studied by previous research. More precisely, this thesis consists of five parts or fields of investigation: 1) the analysis of the notion of solidarity throughout the ages; 2) the study of new and emergent organizational forms; 3) the innovation logics; 4) the firms strategies in industrial communities and consortiums; 5) the rationalization of OSS design.