Michael T. Kiley and John M. Roberts | Nominal interest rates may remain substantially below the averages of the last half-century, as central bank’s inflation objectives lie below the average level of inflation and estimates of the real interest rate likely to prevail over the long run fall notably short of the average real interest rate experienced over this period. Persistently low nominal interest rates may lead to more frequent and costly episodes at the effective lower bound (ELB) on nominal interest rates. We revisit the frequency and potential costs of such episodes in a low-interest-rate world in a dynamic-stochastic-general-equilibrium (DSGE) model and large-scale econometric model, the FRB/US model. Several conclusions emerge. First, monetary policy strategies based on traditional policy rules lead to poor economic performance when the equilibrium interest rate is low, with economic activity and inflation more volatile and systematically falling short of desirable levels. Moreover, the freque ncy and length of ELB episodes under such policy approaches is significantly higher than in previous studies. Second, a risk-adjustment to a simple rule in which monetary policymakers are more accommodative, on average, than prescribed by the rule ensures that inflation achieves its 2 percent objective and requires that policymakers aim at inflation near 3 percent when the ELB is not binding. Third, commitment strategies in which monetary accommodation is not removed until either inflation or economic activity overshoot their long-run objectives are very effective in both the DSGE and FRB/US model. Finally, our results suggest that the adverse effects associated with the ELB may be substantial at inflation targets near 2 percent if r* is low and monetary policy follows a traditional policy approach. Whether such adverse effects could justify a higher inflation target depends on whether monetary policy strategies substantially different from traditional approaches are feasible and an assessment of the effects of the inflation target on economic welfare.