This study tested a transactional model of reciprocal influences regarding students' peer experiences (peer acceptance, peer rejection, and friends' academic achievement) and students' academic achievement from middle childhood to early adolescence. This longitudinal model was tested on 452 students (198 girls), mostly Caucasian and French speaking, who were assessed yearly from Grades 2 through 7. Structural equation models revealed that, for boys and for girls, higher academic achievement predicted (a) increases in peer acceptance from Grades 2 through 6, (b) decreases in peer rejection from Grades 2 through 4 (through Grade 5 for girls), and (c) increases in friends' achievement from Grades 4 through 7. Also, rejection predicted decreases in academic achievement from Grades 3 through 5. These results suggest that academic achievement is a good predictor of peer group status in middle childhood and that high-achieving students start selecting each other as friends as they enter early adolescence. These data also suggest that peer rejection in childhood may disrupt future academic achievement. Possible mediating mechanisms, as well as peer selection and influences in the context of social development, are discussed. (Contains 3 figures and 4 tables.)