Does the death penalty provide greater deterrence of murders beyond that afforded by a sentence of life imprisonment? This question has been actively debated for centuries, with those arguing that capital punishment is a more severe punishment that will provide greater deterrence opposed by those who argue that state-sanctioned executions provide an environment conducive to unsanctioned homicides. Alternatively, some have argued that the death penalty is not as dreadful to potential murderers as the thought of life imprisonment or that the death penalty is less cost-effective than its alternatives. In the past half-century, this debate has turned from social theorists to empiricists. Given the availability of relatively high-quality data on American murder rates, executions, criminal justice statistics, and other relevant control variables as well as the number of researchers conducting sophisticated econometric studies over the last thirty years, one would think that a consensus would have emerged about the answer to this ostensibly simple question. Our aim in this paper is not to provide a single “best” estimate of the impact of the death penalty on murder, but rather to provide a systematic review of the issues confronting researchers working on this question, as well as to review the state of the recent and growing literature on the deterrence question.