The debate over the size, scope and causes of the homicide increase in 2015 has been largely free of systematic evidence. This paper documents the scale of the homicide increase for a sample of 56 large U.S. cities; examines three plausible explanations of the homicide rise (an expansion of urban drug markets fueled by the heroin epidemic, reductions in incarceration resulting in a growing number of released prisoners in the nation's cities, and a "Ferguson effect" resulting from widely publicized incidents of police use of deadly force against minority citizens); and concludes with a call for the more frequent and timely release of crime information to address crime problems as they arise.