Since the 2001 recession, average core in ‡ation has been below the Federal Reserve's 2% target. This de ‡ationary bias is a predictable consequence of a low nominal interest rates environment in which the central bank follows a symmetric strategy to stabilize in ‡ation. The de ‡ationary bias increases if macroeconomic uncertainty rises or the natural real interest rate falls. An asymmetric rule according to which the central bank responds less aggressively to above-target in ‡ation corrects the bias and allows in ‡ation to converge to the central bank's target. We show that adopting this asymmetric rule improves welfare and reduces the risk of self-ful…lling de ‡ationary spirals. This approach does not entail any history dependence in setting the policy rate or any commitment to overshoot in ‡ation after periods in which the lower bound constraint was binding.JEL Codes: E31, E52, E62, E63, D83 Keywords: De ‡ationary bias, asymmetric rules, opportunistic re ‡ation, welfare, natural rate, zero lower bound, disanchoring of in ‡ation expectations, in ‡ation targeting, liquidity traps, macroeconomic uncertainty.Emails: