The findings for the 3-year period 1987-90 show that gang-related, high-crime neighborhoods are of three types: "turf hot spots," where gangs fight over territorial control; "drug hot spots," where gang-motivated drug offenses are prevalent; and "turf and drug hot spots," where gang-motivated crimes relate to both. Gang involvement in violence and homicide was more often turf-related than drug- related. Only eight of 288 gang-motivated homicides were related to drugs. The city's four largest street gangs were associated with most of the street-gang crime. Representing 51 percent of street-gang members, they accounted for 69 percent of recorded criminal incidents. The rate of gang- motivated crimes in the two most dangerous areas was 76 times that of the two safest. A gun was the weapon used in nearly all gang-motivated homicides. These findings suggest that programs to reduce nonlethal gang violence must target the specific gang problems in each neighborhood. Also, effective intervention strategies must have up-to-date information. 6 exhibits, 21 notes, and 13 references