T he state of the labor market, employment and unemployment, playsan important role in the deliberations of policymakers, the FederalReserve Bank included. Over the last 30 years, economic theory has led to substantial progress in understanding the mechanics of business cycles. Much of this progress in macroeconomics has been associated with the use of calibrated dynamic equilibrium models for the quantitative analysis of aggre-gate fluctuations (Prescott [1986]). These advances have mainly proceeded within the Walrasian framework of frictionless markets. For the labor mar-ket, this means that while these theories contribute to our understanding of employment determination, they have nothing to say about unemployment. Policymakers care abou...