Part of a special issue on why crime is decreasing. The writers discuss the extent and causes of the decline in life threatening violence in New York City over a five-year period. In its relative and absolute magnitude, the falls in homicide in New York after 1992 were by far the biggest in the city's postwar history. The patterns for homicide during the decline differ in terms of location, weapon, and demography. The patterns show that there are two separate trends in nongun and gun homicides. The decline in gun homicides could probably be attributed to police intervention, but the decline in nongun homicides remains a mystery.