This study tests the claim that police legitimacy affects the prevalence of homicide. Using a cross-national time-series dataset of 100 countries, I conduct a statistical analysis of the association between the extent to which the public perceives the police as legitimate and the homicide rate. The analysis suggests that police legitimacy has a substantial, negative association with homicide rates, consistent across different sources of homicide data and controlling for a variety of economic, political, and demographic variables. The paper provides evidence that police legitimacy is related to violent behavior, and that this relationship is generalizable across a wide range of contexts, but more pronounced in non-high-income and comparatively unequal countries.