The United States uses two national data collection systems to track detailed information on homicides: the Federal Bureau of Investigation’s Supplementary Homicide Reports and the Centers for Disease Control and Prevention’s Fatal Injury Reports. Both measures were developed as part of a federal effort to improve national statistical systems in the early twentieth century and have gone through a number of changes since then to improve their consistency and coverage. Each program provides valuable information on the nature, trends, and patterns of homicides in the United States. Although the two measures generally capture information on the same types of events, they are designed for distinct purposes and collect different types of information. In combination, however, they produce a fairly comprehensive understanding of homicide, the most serious form of violence.