Aggressive Behavior in Adolescents and Emerging Adults: The Psychometrics of the Portuguese Brief Peer Conflict Scale (Brief-PCS).

The Brief Peer Conflict Scale (Brief-PCS) has been shown to be psychometrically suitable for assessing the combination of the forms and functions of aggressive behavior in adolescence. However, its validity, invariance, and utility across other age groups remains unexplored. The current study aims to evaluate the psychometric properties of the Brief-PCS in community samples of adolescents and emerging adults, and to compare self-reported aggression across these age groups and by sex. A sample of 891 individuals (58.4% female, Mage = 16.69) completed the Brief-PCS and additional measures assessing psychopathy characteristics, forms of aggression, and overall aggression. Confirmatory factor analyses supported the four-factor measurement model (i.e., proactive overt, reactive overt, proactive relational, and reactive relational aggression) as the best fit for the data. Evidence also supported the scales' internal consistency and convergent validity. This four-factor measurement model proved to be invariant across age groups and sex. Males reported being overall more aggressive than females, and adolescents reported more aggressive behaviors than emerging adults, except for proactive relational aggression. These findings extend prior research by confirming the Brief-PCS as a psychometrically sound and developmentally invariant tool, enhancing its value for examining both theoretical and applied aspects of aggression throughout the lifespan.