Gangs have been observed to possibly progress through three generations. A close analysis of urban street gangs shows that some of these criminal enterprises have transitioned from traditional turf gangs, to market-oriented drug gangs, to a new third generation that combines political and mercenary aims. As gangs transverse this generational shift, their progress can be charted by three factors: the interaction of politicization, internationalization, and sophistication. The progress of gangs along this generational continuum is a consequence of technological and organizational changes which enhance the power of relatively small groups. These three gang generations are summarized as follows: (1) First Generation Gangs--traditional street (or prison) gangs with a turf orientation; (2) Second Generation Gangs--engaged in business, they are entrepreneurial and drug-centered; and (3) Third Generation Gangs (3 GEN Gangs)--evolved political aims and the most complex gangs; to date, most 3 GEN Gangs have been primarily mercenary in orientation. This paper recounts the typology of the three generations of gang evolution and explores recent trends in transnational street and prison gangs. 79 footnotes