Social preferences and social influence effects ("peer effects") are well documented, but little is known about how peers shape social preferences. Settings where social preferences matter are often situations where peer effects are likely too. In a gift-exchange experiment with independent...

In small groups norm enforcement is provided by mutual punishment and reward. In large societies we have enforcement institutions. This paper shows how such institutions can emerge as a decentralized equilibrium. In a first stage, individuals invest in a public enforcement technology. This...