Consider an agent who can costlessly add mean-preserving noise to his output. To deter such risk-taking, the principal optimally offers a contract that makes the agent's utility concave in output. If the agent is risk-neutral and protected by limited liability, this concavity constraint binds...

This article surveys the literature on principal-agent problems with moral hazard that gained popularity following the seminal works of Mirrlees (1976), Holmström (1979), and others. This literature is concerned with designing incentives to motivate one or more workers—typically by paying for...