One of the more robust findings in criminology is that gang members commit more crimes than do nongang youth. Evidence from this study primarily supports the facilitation model wherein social processes inherent in the group accelerate individual rates of crime. There was some evidence to support the enhancement model wherein those who join gangs exhibit higher levels of premembership offending and delinquency, but during active gang membership, their rates further increase. Though a great deal has been learned regarding the impact of gang membership on an individual’s criminality, little is known about how this impact translates at either the city or neighborhood levels. The role of gangs as a local crime generator or attractor is a missing component in the study of gangs. Utilizing the “emergent gang city” of Philadelphia, PA, this article examined the following questions: (1) how did the presence of a gang affect the overall level of crime within a community; (2) did the formation of gangs affect the commission of different types of crime; and (3) did gangs displace some types of crimes while attracting others? Tables, figures, notes, and references