The study sample consisted of 5,541 gang-related homicides committed in the jurisdictions of the Los Angeles Police Department and Los Angeles Sheriff's Department during the reporting period. Over the course of the study period, the proportion of all murders that were related to gangs increased from 18 percent to 43 percent. Over 85 percent of the murder victims were between the ages of 15 and 34 years, 93 percent were black or Hispanic, 93 percent were male, 64 percent were affiliated with gangs, and 25 percent were killed during drive-by shootings. In 1994, nearly 95 percent of the gang-related homicides were committed using firearms, compared to 71 percent in 1979. The use of semiautomatic handguns in these murders also increased dramatically during the study period. 2 tables, 5 figures, and 38 references