In this paper we study experimentally four remedies to overcome inefficiencies that arise from the incompleteness of contracts. These remedies are reciprocity, repeated game effects, social embeddedness, and incentive contracts. In our baseline treatment we find that reciprocity is a powerful...

Field evidence suggests that agents belonging to the same group tend to behave similarly, i.e., behavior exhibits social interaction effects. Testing for such effects raises severe identification problems. We conduct an experiment that avoids these problems. The main design feature is that each...