Does a “bad apple” spoil the bunch? The impact of low-achieving students on non-cognitive outcomes

This paper investigates whether the presence of low-achieving classmates affects the noncognitive outcomes of regular students in junior high school. Exploiting random assignments of teachers and students to classes, we show that having classmates who had ever repeated a grade in primary school improves students' mental health and social skills, and the positive peer effects are concentrated among students with a longer duration of peer exposure and students from low socioeconomic backgrounds. Mechanism analysis reveals that the improved teacher–student and student–student interactions contribute to the enhancement of noncognitive outcomes. • Low-achieving classmates improves both mental health and social skills of regular students. • The positive peer effects are concentrated among students with a longer duration of peer exposure and students from low socioeconomic backgrounds. • The improved teacher–student and student–student interactions contribute to the enhancement of noncognitive outcomes.