Whilst peer facilitation is deemed to be a beneficial alterative strategy in an asynchronous online discussion, a review of the literature indicates that previous studies have primarily focused on the instructor as the facilitator. Inquiries into the roles that student facilitators perform and strategies they deploy to promote meaningful dialogues and participation in a student-led online discussion board have not been widely explored. Using posted messages of seven student facilitators in a peer-moderated online discussion forum, this study aimed to address the gap in the literature. Content analysis of the data revealed that the student moderators played four major roles during the discussions: 1) a knowledge constructor who actively engaged in a collective inquiry and contributed to a deeper understanding of a subject matter; 2) a team builder who expended considerable efforts to create group cohesion to achieve their learning objectives as a team; 3) a motivator who encouraged and inspired team members to engage in and contribute to the discussion; 4) an organiser who managed and monitored each phase of the discussion and orchestrated the subsequent group oral presentation. The findings suggest that assigning students to lead online discussions is an effective strategy to foster learner autonomy and nurture student leaders. The paper concludes with pedagogical implications and directions for future research.