Japan’s encounter with deflation and near‐zero‐interest short‐term interest rates in the 1990s led to a surge in research on the implications of the zero lower bound (ZLB) on nominal interest rates for monetary policy around the end of that decade. Based on model simulations, the literature at that time identified a number of key implications of the ZLB (see Orphanides and Wieland [2000], Reifschneider and Williams [2000, 2002], Eggertsson and Woodford [2003], and references therein). First, with low inflation targets of the kind followed by many central banks, the ZLB will frequently be a binding constraint on monetary policy. That is, Japan’s example is not an outlier but rather a harbinger for the future. Second, at inflation targets of 1% or lower, lowering the inflation target comes at a cost of higher variability of output and inflation, although the effects on inflation variability are relatively small. This analysis provides an argument for maintaining a positive inflation target cushion above 1%. Third, in rare instances of severe prolonged recessions accompanied by deflation, standard open market operations will be insufficient to bring the inflation rate back to target, andalternative sources of stimulus to the economy, such as fiscal policy, will be needed. Fourth, central banks can significantly reduce the effects of the ZLB onmacroeconomic stability by modifying their policy actions and communication to the public when the ZLB threatens to constrain policy. Specifically, policies that cut rates aggressively when deflation is a risk and promise to temporarily target a higher rate of inflation following episodes where the ZLB binds were found to greatly reduce the effects of the ZLB in model simulations. In the decade since this researchwas initiated, the ZLB has gone froma theoretical issue applying to Japan to one that plagues many industrialized economies. Indeed, an era of overwhelming confidence in monetary policy’s power to tame the business cycle while delivering low and stable inflation has been replaced by fears that the global economy could