The concept of gang aggression oftentimes elicits images of brutal intergang violence. In reality, gang-related aggression can vary widely, can have various motivations and causal factors, and includes interpersonal as well as intergroup aggression. This study examined the tendency of UK youth to engage in displaced aggression (aggression aimed at undeserving targets) and examined the relationship among gang affiliation, ruminative thought, and aggression levels. Students in three London schools were asked to complete a questionnaire that assessed levels of gang affiliation, rumination about aversive events, and a tendency to engage in displaced aggression. Our analyses found a three-way interaction between gang affiliation, rumination, and gender, such that males who were high in affiliation and rumination had the greatest tendency to displace aggression toward innocent others. Additionally, it was shown that rumination could account for a significant part of the correlation between gang affiliation and displaced aggression. Furthermore, regression analyses showed that even after controlling for trait aggression, anger, hostility, and irritability, rumination remained a significant predictor of displaced aggression. The implications for understanding gang-related aggression and for conducting future research in this area were discussed. Aggr. Behav. 38:89-97, 2012. © 2011 Wiley Periodicals, Inc.