In many natural environments, carefully chosen peers influence individual behavior. In this paper, we examine how self-selected peers affect performance in contrast to randomly assigned ones. We conduct a field experiment in physical education classes at secondary schools. Students participate...

This paper studies how peers in school affect students' mental health. Guided by a theoretical framework, we find that increasing students' relative ranks in their cohorts by one standard deviation improves their mental health by 6% of a standard deviation conditional on own ability. These...

This paper studies how peers in school affect students’ mental health. Guided by a theoretical framework, we find that increasing students’ relative ranks in their cohorts by one standard deviation improves their mental health by 6% of a standard deviation conditional on own ability. These...