Online courses frequently use discussion forums to enhance student engagement, an approach that is critical to fostering positive student learning outcomes. Because discussion forums are common in online classes, many instructors rely on summary statistics and self-reported measures to assess student engagement. However, these metrics overlook the structural and relational dimensions of student interactions in discussion forums. To complement those other metrics, this study uses social network analysis to examine interactions in a discussion forum to expose the structural and relational dimensions of student interactions. We aggregated data on student interactions in a discussion forum for an undergraduate class with 31 enrolled students. The graphical representation of student interactions in the discussion forum revealed the social positions and roles of students and exposed the strengths and weaknesses in the structural and relational ties. Mathematical analysis accurately measures student interactions in the forum using measures of centrality. Both of those analyses enabled the description and comparison of interactions at the group and individual levels. Social network analysis is a practical method that adds another perspective to our understanding of student interactions in discussion forums. The outcomes of social network analysis can help instructors design courses, devise appropriate teaching interventions, and effectively use forums to engage students to improve learning outcomes.