This study examined the role that peer groups play in shaping students' academic re-engagement across their first year in middle school and whether influences are stronger from peers with whom students remained affiliated over time. Data were collected on an entire cohort of 366 sixth graders (48% female) in a small town. Students reported on their behavioral re-engagement--or persistence following academic problems or failure, on the extent to which they experienced academic setbacks, and on their teachers' involvement. Teachers rated students' academic engagement. Peer groups were identified in fall and spring using socio-cognitive mapping, distinguishing fluid peers (i.e., group members in fall only) and stable peers (i.e., members in both fall and spring). Peer group profiles of re-engagement were calculated for fluid peers, stable peers, and both combined. Results showed that the overall peer group profiles of re-engagement in fall did not predict changes in students' re-engagement over the school year when unstable members were included. However, when modeled separately, stable peer group profiles of re-engagement were a positive predictor of changes in students' own re-engagement, whereas profiles of fluid peers' re-engagement were not. The findings suggest that peer group members with whom students maintain consistent group affiliations across the year play a central role in supporting students' re-engagement when overcoming academic difficulties.