The goal of this study was to examine the distinctiveness of reactive aggression (RA) and proactive aggression (PA) from a variable- and person-based approach, their psychosocial correlates and behavioral outcomes, and analyze their replicability across two samples of adolescents. The forensic sample was composed of 231 juvenile offenders and the community sample included 321 youth. At a variable-based level, the results of the factor analysis supported the original two-factor model of aggression, and RA and PA showed differential associations with a set of psychosocial correlates and behavioral outcomes. At a person-based level, three subgroups were identified, namely low aggression, moderate RA, and mixed aggression. The mixed aggression group showed the most severe profile in both samples. These results support the distinctiveness of RA and PA at a variable-based level but lead to consider PA as a severity marker rather than a distinct subgroup at a person-based level.