We administered the Measure of Aggression, Violence, and Rage in Children (MAVRIC; Bass, Geenens, & Popper, 1993a, 1993b), a questionnaire assessing the severity of reactive, impulsive aggression, to 28 prepubertal psychiatrically hospitalized children and 54 prepubertal lowrisk nonpatients and their mothers. Cross-informant reliability was supported between the MAVRIC-Child Version (MAVRIC-C; Bass et al., 1993a) and MAVRIC-Parent Version (MAVRIC-P; Bass et al., 1993b), r = .62, p < .001. Convergent validity was supported with the Aggressive Behavior factor of the Child Behavior Checklist (Achenbach, 1991a) for the MAVRIC-C, r = .62, p < .001, and MAVRIC-P, r = .74, p < .001. Both versions were also associated with disruptive behavior disorders, inpatient status, and assaultive behavior. We discuss the differences in the perception of aggression as a function of informant.