This article examines the optimal choice of monitoring intensity when workers face external incentives (incentives that are not provided by the firm), such as tips, satisfaction from working well, or the desire to build reputation in order to be more attractive to other employers. Increase in...

Some economists believe that social norms are created to improve welfare where the market fails. I show that tipping is such a norm, using a model in which a waiter chooses service quality and then a customer chooses the tip. The customer's utility depends on the social norm about tipping and...