Early adolescents' academic self-concept formation: Do classmates or friends matter most?

• The BFLPE model explains individual differences in academic self-concept.
• The simultaneous effect of multiple reference frames is understudied.
• This study shows that classmates were a more dominant reference frame than friends.
• Students tend to rely on the most informative frame and less on the most local one.

The big-fish-little-pond effect model explains individual differences in equally achieving students' academic self-concept by the achievement level of their reference group. Taking into account the multitude of reference groups in students' everyday school life, this study investigates which reference frame (i.e., classmates or friends) matters most for students' academic self-concept. Our sample comprised 2987 students (50% boys) from Grade 6 in 112 elementary schools (174 classes). Three dimensions of academic self-concept (i.e., global academic, math, and language self-concept) were considered. Using multilevel modeling, we found the predicted negative effects of class-average and friend-average achievement on all three academic self-concept dimensions. When comparing the effect of both group-average achievement variables, we found that friend-average achievement always had a smaller negative effect than class-average achievement. Overall, these results suggest that, when evaluating their academic competencies, students do not primarily rely on the most local comparison source, but on the most informative one.