This paper examines the optimal response of monetary and fi scal policy to a decline in aggregate demand. The theoretical framework is a two-period general equilibrium model in which prices are sticky in the short run and flexible in the long run. Policy is evaluated by how well it raises the welfare of the representative household. While the model has Keynesian features, its policy prescriptions di¤er signi cantly from textbook Keynesian analysis. Moreover, the model suggests that the commonly used "bang for the buck" calculations are potentially misleading guides for the welfare e¤ects of alternative fiscal policies.