Evaluating Central Banks? tool kit: Past, present, and future *

We develop a structural DSGE model to systematically study the principal tools of unconventional monetary policy - quantitative easing (QE), forward guidance, and negative terest rate policy (NIRP) - as well as the interactions between them. To generate the same output response, the requisite NIRP and forward guidance interventions are twice as as a conventional policy shock, which seems implausible in practice. In contrast, QE an endogenous feedback rule can alleviate the constraints on conventional policy posed the zero lower bound. Quantitatively, QE1-QE3 can account for two thirds of the observed decline in the "shadow" Federal Funds rate. In spite of its usefulness, QE does not come without cost. A large balance sheet has consequences for different normalization plans, efficacy of NIRP, and the effective lower bound on the policy rate.