The current study examined the best friendships of aggressive and nonaggressive boys (N = 96 boys, 48 dyads, mean age = 10.6 years). Friends completed self-report measures of friendship quality, and their interactions were observed in situations that required conflict management and provided opportunities for rule-breaking behavior. Although there were no differences in boys' self-reports of friendship quality, observers rated nonaggressive boys and their friends as showing greater positive engagement, on-task behavior, and reciprocity in their interactions compared with aggressive boys and their friends. Aggressive boys and their friends provided more enticement for rule violations and engaged in more rule-breaking behavior than did nonaggressive boys and their friends. Also, the intensity of negative affect in observed conflicts between aggressive boys and their friends was greater than that between nonaggressive boys and their friends. The findings suggest that friendships may provide different developmental contexts for aggressive and nonaggressive boys.