Instructor participation plays a crucial role in asynchronous online discussions, as the approach taken can potentially impact student performance. This study compared two instructor participation approaches: replying to student posts on public discussion boards and commenting on student posts on private grade pages. It examined the impact on both the quantity of student participation and the quality of student posts. The findings revealed more student-student interactions when the instructor replied directly on discussion boards compared to when the instructor commented on private grade pages, despite both approaches leading to an interconnected social network. The number of student posts and the overall quality of student posts did not show a significant difference between the two approaches. Nonetheless, both approaches contributed to a gradual improvement in the quality of student posts over time. Additionally, when the instructor commented on grade pages, students' focus shifted gradually from social communication to knowledge construction in their posts.