This article uses a DSGE framework to evaluate the role of monetary policy in determining the likelihood of encountering the zero lower bound. We …nd that the probability of experiencing episodes of being at zero lower bound depends almost exclusively on the monetary policy rule. A policy rule, such as the one proposed by Taylor (1993) which is based on the dual mandate is highly likely to lead to episodes of zero short-term interest rates if the central bank is not committed to its in‡ation target. Our results on nominal interest rate and in‡ation dynamics do not depend on the particular mechanism that