Purpose: The study seeks to understand what teachers know about students' friend networks and how they use that information for instruction. Design/methodology/approach: This qualitative study relied on interviews and sociograms that teachers drew of students' friend networks. Findings: Our data suggest that teachers' awareness of their students' friend networks varies by their experience and their exposure to students. Also, their use of this information for instruction coalesces around dimensions of grouping and social support. Research limitations/implications: This study took place at one school. To more deeply understand what teachers perceive about their students' friend networks and how they use that information for instruction, more studies could be done with teachers in more schools. Practical implications: Implications might suggest developing teachers' social competence to support their students' learning and development. Originality/value: While studies cited in this paper have explored teachers' knowledge of students' social networks, this study builds on this work by exploring how that information can be useful for instruction. In addition, this study explores the use of teachers drawing sociograms as representations of what they know about students' friend networks.