Participants in Open Source Software (OSS) development projects usually contribute voluntarily without expecting direct compensation for their work. One of the central puzzles raised by the success of OSS is the motivation of the participants; why top-notch programmers choose to write software that is released for no fee. In order to respond to this peculiarity employing a meta-research method, we first identify and review theoretical perspectives from diverse disciplines including economics, sociology, political science, anthropology, psychology, and management. Then, we suggest a comprehensive framework that provides a holistic understanding of the puzzle in question. Reviewing key empirical studies based on the suggested framework, we also suggest a future research agenda.