Drawing from an ecological framework, there has been growing attention on the role of peers in accounting for adolescents' homophobic behavior. In this study, we considered whether individuals' homophobic behavior could be attributed to their peers' collective levels of aggression, sexual prejudice, and importance placed on their sexual orientation identity among 437 high school students (89% White, 61% female, mean age = 15.72 years) in 62 peer groups identified through social network analysis. Using multilevel modeling, we found that individuals in more homophobic and aggressive peer groups engaged in even more homophobic behavior than accounted for based solely on their own individual prejudice attitudes and aggressive behavior. Furthermore, individuals' sexual prejudice was a stronger predictor of their engagement in homophobic behavior for those in groups whose peers collectively placed greater importance on sexual orientation identity and were more aggressive. These findings begin to provide a fuller sense of how individual and peer attributes combine and interact in ways that account for individuals' engagement in homophobic behavior.