This paper aims at opening the black box of peer effects in adolescent weight gain. Using Add Health data on secondary schools in the U.S., we investigate whether these partly flow through the eating habits channel. Adolescents are assumed to interact through a friendship social network. We...

We investigate the effect of peer group composition on language improvement in language classes for adults. Using unique survey data of migrants participating in an intensive language course in Germany, we find that the age and skill composition of groups affect skill acquisition as assessed by...

Ethnic diversity is typically measured by the well-known Hirschman-Herfindahl Index. This paper discusses the merits of an alternative approach, which is in our view better suited to tease out why and how ethnic diversity matters. The approach consists of two elements. First, all existing...