-post punishments or rewards to align incentives. Field data is mixed on whether, and to what extent, such informal incentive …, the impact of ex-post incentives on informal contracts between principals and agents in bargaining environments in which …

, which offer important new insights into the interaction of contract choices, fairness and incentives. … provide powerful incentives and are superior to explicit incentive contracts when there are some fair-minded players. But …

We show that concerns for fairness may have dramatic consequences for the optimal provision of incentives in a moral … incentives and become superior when there are also fair-minded players. These predictions are strongly supported by the results …