In an economy without informational and other distortions, entrepreneurs and workers can write labor contracts that support a Pareto optimal allocation of resources. This paper is an attempt to characterize contracts when enterpreneurs are better informed about the state of nature than are their workers. Asymmetric information generally results in a suboptimal allocation of both risk and worker effort; in particular, if consumption and leisure are perfect substitutes, employment will be less than fully Pareto optimal in all but the most favorable states of nature.

This introductory essay offers a brief guided tour of the main developments in the theory of implicit contracts, from its inception to the present. It is not intended as a survey but, rather, as an appraisal of the progress that has been made, the difficulties that remain, and as an outline of the microeconomic and macroeconomic issues that seem to invite additional work.