Peer nominations for behavioral reputation, likability, and friendship were examined after 4 years of an ongoing randomized, controlled prevention trial designed to interrupt the developmental trajectory of young aggressive children by improving peer relations. Participants included 125 moderately to highly aggressive children (program and control) and their 4th-grade classmates (N = 1,489). Results indicated that program children, as compared to controls, obtained higher reputation scores on leadership and social etiquette and chose friends with lower aggression. Self-reported quality of friendship also differed between groups, with program children reporting more companionship and recreation, program girls reporting more validation and caring, and severely aggressive program children reporting less aggression toward others than their control counterparts. These findings provide evidence for the generalization of program effects to a natural peer setting.