The aim of this study was to further explore the psychometric properties of the Serbian adaptation of the Reactive-Proactive Aggression Questionnaire (RPQ) using item response theory to gain insight into measurement precision (information) and differential item functioning (DIF) across sexes. The sample consisted of 1,268 community-dwelling adults. Results confirmed a 2-factor structure and showed good reliabilities. Information of the reactive aggression scale covered a wider range of traits, but in the case of proactive aggression, it was limited in above-average and average levels of traits. Additionally, the impact of DIF on total scores was negligible. Furthermore, latent profile analysis showed that a clear proactive aggression profile could not be isolated, indicating that proactive aggression cooccurs with reactive aggression. However, both scales evidenced differential correlates. Reactive aggression was positively associated with anger and hostility and was negatively associated with agreeableness and forgiveness, whereas proactive aggression was positively related to indirect aggression and negatively to honesty-humility and emotionality. Taken together, although information for the proactive aggression scale is problematic, results overall support the 2-factor model of the RPQ and unbiased scale scores across sexes, and add further to the validity and cross-cultural generalizability of this scale.