Traditional street gangs operate under loose leadership; they have ill-defined roles and focus on loyalty and turf protection. They engage in a broad range of opportunistic criminal activity and intergang rivalry. The more entrepreneurial, drug-centered gang emerges as a second-generation organization. It is interested in market protection, focuses its criminal endeavors on drugs as a business, and has greater centralization of leadership. It sometimes operates in a multistate context, conducts more sophisticated operations, and may embrace violence in the form of quasi-terrorism. The third-generation street gang is a sophisticated, global-type group that embraces either quasi-terrorism or true terrorism. Thus, its members are netwarriors who truly challenge the nation-state. No gang currently falls squarely into the third-generation category, although some gangs are moving in that direction. Increased interaction between gangs at each level of evolution will stimulate the crossover of still more gangs into the second and third generations. Turf will remain the focus for most gangs; some will enter the drug trade, while others will embrace violence for profit of political gain. The framework of generational evolution presented here allows an assessment of the level of development and corresponding threat presented by these groups.