The open source model of software development has received substantial attention in the industry and popular media; nevertheless, critics frequently contend that open source software are inferior in quality compared to closed source software because of lack of incentives and project management, while proponents argue the opposite. This paper examines this quality debate by modeling and analyzing software development under open and closed source environments. The results show no dominant quality advantage of one method over another under all circumstances. Conditions under which each method can generate higher quality software are examined.