Although whites were the predominant racial/ethnic group in later onset localities, racial/ethnic mixing may be a defining characteristic of such gangs. Gang members in the earliest onset localities not only were involved in property crimes, but also were very likely to be involved in violent crimes (homicide, aggravated assault, robbery, and use of firearms). In contrast, gang members in the latest onset localities were most likely to be involved in the property crimes of burglary/breaking and entering and larceny/theft, although they were far less likely to be involved in motor vehicle theft. Gang-member involvement in drug trafficking was lower in the later onset jurisdictions than in the earlier onset jurisdictions; however, in the later onset jurisdictions, the level of individual-member involvement in drug sales was greater than the overall level of gang control of drug distribution. The findings suggest that by taking action as soon as a gang problem is discovered, it may be possible to interrupt the gangs' developmental progression from involvement in general delinquency and property crimes to involvement in serious, violent activities. 4 figures, 5 notes, and 53 references