Peers are considered important for adolescents’ educational achievement and attainment, though little conclusive evidence demonstrate peer comparison effects. Using school and year fixed-effects models to account for peer group selection and comprehensive Danish administrative data on more than 260,000 students, across six cohorts, this study provides evidence of the so-called frog pond effect on the choice of secondary education among adolescents in Denmark. The frog pond effect is based upon a social comparison mechanism with heterogeneous effects. Through peer achievement, the author investigates the heterogeneous effects and show that peer achievement has different effects for low- and high-achieving students on choice of secondary education. The results shows that low-achieving students benefit from having high-achieving peers, while high-achieving students are negatively affected by their high-achieving peers, although only to a small extent. These findings lend support to the frog pond effect for high-achieving students.