A common claim is that open source software development produces higher quality software at lower cost than traditional commercial development To validate such claims, researchers have conducted case studies of "successful" open source development projects. This case study of the FreeBSD project provides further understanding of open source development. The FreeBSD development process is fairly well-defined with proscribed methods for determining developer responsibilities, dealing with enhancements and defects, and for managing releases. Compared to the Apache project, FreeBSD uses a smaller set of core developers that implement a smaller portion of the system, and uses a more well-defined testing process. FreeBSD and Apache have a similar ratio of core developers to (1) people involved in adapting and debugging the system, and (2) people who report problems. Both systems have similar defect densities, and the developers are also users in both systems.