This study presents the psychometric properties of the Peer Aggressive and Reactive Behaviors Questionnaire (PARB-Q), a self-report questionnaire to measure child overt aggression (PA) and reaction to peer aggression (RPA). Participants were 587 Italian elementary school children, aged 7-10 years (51.5% female). Exploratory and confi rmatory factor analyses presented a one-factor solution for the PA scale and a three-factor solution for the RPA scale (reactive aggression, seeking teacher support and internalizing reaction), presenting adequate reliability and goodness-of-fi t indexes for both scales. Criterion validity presented satisfactory evidence. The PARB-Q appears to be a psychometrically sound tool to evaluate aggressive behavior and reactions to peer aggression in elementary school children.