There is now an extensive literature on "gift exchange" showing that when principals and agents can trade "gifts" (rewards that should not emerge in a competitive equilibrium), exchange becomes more efficient. However, it is not obvious how gift exchange should be organized if the principal's...

Because costly punishment is not credible, subgame perfection suggests that punishment will not deter free riding, regardless of the size or structure of groups. However, experiments show that people will punish free riders, even at considerable cost. To examine the implications of agents who...

The enforcement of social norms often requires that unaffected third parties sanction offenders. Given the renewed interest of economists in norms, the literature on third party punishment is surprisingly thin, however. In this paper, we report on the results of an experiment designed to...

There has been little systematic study of the mechanisms typically used to raise money for charity. One of the most common is the simple raffle in which participants purchase chances to win a prize at a constant price. We conduct a field experiment randomly assigning participants to four raffle...