E ver since the U.S. federal–state system of unemployment insurance wasfounded in the 1930s, it has provided partial, temporary replacement ofwages to eligible workers who lose jobs “through no fault of their own ” (as determined by state-level regulations). Unemployment insurance is one of the largest social insurance programs in the United States, with benefits paid totaling about $34 billion in 2004. This figure is considerably smaller than for Social Security, Medicare or Medicaid, but it exceeds spending on such major programs as Workers ’ Compensation, Temporary Assistance to Needy Families (TANF) or Food Stamps. In this paper we focus on the ways economic theory can help us understand the challenges that this complex program is likel...