Many types of economic and social activities involve significant behavioral complementarities (peer effects) with neighbors in the social network. The same activities often exert externalities that cumulate in "stocks" affecting agents' welfare and incentives. For instance, smoking is subject to...

The paper studies the impact of ethnic diversity on social participation of young people. We first propose a theoretical model in which the agents choose between structured and unstructured social activities by taking into account the ethnic composition of the groups they join. We test our...