Sex biases in adult aggression have been well studied and commonly arise when resources which affect survival or lifetime reproductive success are less abundant or more valuable for individuals of one sex. Despite the prevalence of sex biases in adult aggression, evidence for sex biases in juvenile aggression is scant. Here, we present evidence for female-biased juvenile aggression in cooperatively breeding pied babblers (Turdoides bicolor). Unlike most cases of non-lethal sibling aggression, juvenile aggression in pied babblers does not seem to be determined by food availability. Instead, we found that juvenile aggression was related to adult dispersal patterns. This study shows that females that were more aggressive as juveniles attempted dispersal earlier than less aggressive females. Potential explanations for the association between juvenile aggression and adult dispersal patterns are discussed.