Introduction / George A. Akerlof, Janet L. Yellen -- The Theory of Underemployment in Densely Populated Backward Areas / Harvey Leibenstein -- Another Possible Source of Wage Stickiness / Robert M. Solow -- Equilibrium Unemployment as a Worker Discipline Device / Carl Shapiro, Joseph E. Stiglitz -- Involuntary Unemployment as a Principal-Agent Equilibrium / James E. Foster, Henry Y. Wan, Jr. -- Labor Contracts as Partial Gift Exchange / George A. Akerlof -- A Model of the Natural Rate of Unemployment / Steven C. Salop -- Job Queues and Layoffs in Labor Markets with Flexible Wages / Andrew Weiss -- Hierarchy, Ability, and Income Distribution / Guillermo A. Calvo, Stanislaw Wellisz -- Incentives, Productivity, and Labor Contracts / Edward P. Lazear, Robert L. Moore -- Work Incentives, Hierarchy, and Internal Labor Markets / James M. Malcomson.