Open source (OS) software development has been the subject of heightened interest among organizational scholars because of the novel social coordination practices that signal a departure from traditional proprietary software development. We propose that trust among group members in open source development groups (OSDGs) plays a key role in facilitating their success. Trust is important in this context because of the risk of opportunistic behavior by other members who volunteers may not have met and may never expect to meet, as well as a lack of explicit market contracts or common organizational affiliation. The open source community is differentiated by a coherent ideology that emphasizes a distinct set of interrelated norms, beliefs, and values. These serve to create incentives for open source practices that eschew conventional transactional norms in favor of a gift culture and a focus on reputations. In this study, we primarily examine the role of the shared ideology in enabling the development of affective and cognitive trust in OSDGs. We further examine how this trust leads to desired outcomes ñ group efficacy and effectiveness. The study is based on exploratory interviews, examination of archival records and a preliminary survey to understand the specific conditions of open source efforts on which this work-in-progress report is based. This is being followed-up by empirical testing of our research model through a survey of a broad variety of OSDGs. This study would contribute to a clarification of the role of trust in enabling software groups to work effectively and help to understand the bases of trust in ideology-permeated groups.