The present study investigated the extent to which peer group similarity in school burnout is due to peer group influence and the extent to which it is due to peer group selection. Moreover, the roles of academic achievement and gender in school burnout were examined. A total of 611 ninth graders were examined at the beginning of the final term of comprehensive school, and 614 were examined at the end of the final term. The results of the Multilevel Latent Growth Modeling showed that peer group influence was responsible for peer group similarity, but no evidence was found for peer group selection. The results showed further that high academic achievement protected group members against an increase in school burnout.