This study investigated the big-fish-little-pond effect (BFLPE) on mathematics-related achievement emotions (enjoyment, pride, anger, anxiety, shame, hopelessness, and boredom) among adolescents (N = 1322) using multilevel modeling, controlling for the effects of gender and classroom size. The results indicated that only pride was influenced by the BFLPE. Hence, adolescents reported less pride in mathematically higher-performing classrooms (higher classaverage). The cross-level interaction effects indicated that the BFLPE varies across mathematics performance levels and gender. In mathematically higher-performing classrooms, adolescents with lower mathematics performance reported less pride and more shame, whereas adolescents with higher mathematics performance reported less enjoyment and more boredom. Additionally, males reported more shame in higher-performing classrooms. We discuss the practical implications of supporting achievement emotions in higher-performing classrooms.