This investigation examined the associations between maltreatment and aggression using a gender-informed approach. Peer ratings, peer nominations, and counselor reports of aggression were collected on 211 maltreated and 199 nonmaltreated inner-city youth (M age = 9.9 years) during a summer day camp. Maltreatment was associated with aggressive conduct; however, these effects were qualified by gender, maltreatment subtype, and the form of aggression under investigation. Findings revealed that maltreatment was associated with physical aggression for boys and relational aggression for girls. Physical abuse was associated with physically aggressive behaviors, but sexual abuse predicted relational aggression for girls only. Findings suggest that investigating the interaction between familial risk and gender is important in understanding aggressive behaviors of boys and girls.