How Peers Inform Adolescents' Academic Self-Concept and Achievement: A Three-Wave Random-Intercept Cross-Lagged Panel Analysis.

Adolescents' everyday peer relationships provide proximal academic information, yet peer-effects research centered on aggregate achievement offers limited insight into these immediate contexts. This study examined longitudinal relations among high-interaction peers' academic performance, adolescents' academic self-concept, and achievement, including gender differences. Three-wave data at three-month intervals were obtained from 1,030 seventh- and eighth-grade Chinese adolescents (Mage = 13.24 years, SD = 0.75 at baseline; 50.39% girls; 48.25% seventh graders). A random-intercept cross-lagged panel model was estimated, with gender moderation examined through multiple-group analyses. Results showed significant positive between-person associations among the three academic variables. At the within-person level, peer academic performance predicted subsequent academic self-concept and achievement, and academic self-concept and achievement were reciprocally related over time. Peer academic performance also indirectly predicted later achievement through academic self-concept and later academic self-concept through adolescents' own achievement. Gender differences were observed in relations with later achievement. By separating stable differences from within-person variation, the study demonstrates positive within-person relations between proximal peers' academic performance and adolescents' subsequent academic self-concept and achievement, underscoring the importance of proximal peer environments for early adolescents' academic development.