This book applies social network analysis and economic theory and methodology in Information Systems research to study three issues associated with open source software projects and their applications in the software industry. It targets at those who are interested in the open source project, and would like to find the implications from social network theory and industrial organization models. To deepen our understanding of the evolution of open source projects, the first study aims to analyze the evolution of open source projects from inception to success or failure by using the theoretical lens of social network analysis. Secondly, we examine the competition between proprietary and open source software. We will answer how commercial software vendors should optimally set the price and design its product when competing with the open source product. The popularity of open source poses competition to proprietary software producers and brings to light a new competing strategy: opening part of the source code. In the third study, we model the competition between two profit-oriented firms, and analyze the optimal strategy of the firm that uses open source as a competing strategy.