This study integrates diverse literatures on peer group influence by conceptualizing and examining the relationship of peer group injunctive norms to the academic adjustment of a large and ethnically diverse sample of rural early adolescents' academic adjustment. Results of three-level hierarchical linear modeling indicated that peer groups were differentiated by injunctive norms for effort and achievement. After accounting for prior adjustment, peer group injunctive norms predicted changes to students' school valuation and effort. Peer group injunctive and descriptive norms were moderately correlated; injunctive norms that were more discrepant from descriptive norms were associated with academic adjustment beyond the associations for descriptive norms. Peer group normative relationships did not differ by gender, ethnic minority status, or school configuration. Implications for understanding peer influence and for educational practice are discussed. (Contains 5 tables and 4 notes.)