The aim of this study was to investigate the adequacy of the reduced version of the Jesness — Revivised Inventory (JI-R) developed in Brazil with the Spanish context. The JI-R is an important forensic psychological assessment tool for adolescents admitted to the juvenile justice system. The specific objectives were to analyse the evidence of reliability of the reduced scales in the Inventory and of the validity of the criterion with the scales of the Big Five Personality Trait Short Questionnaire. The sample consisted of 179 men, adolescents and young people. The reliability of scales was investigated with empirical reliability and the correlation between scores was calculated using Rho de Spearman’s correlation analysis. The results indicate that 11 out of the 12 JI-R scales have adequate reliability rates and that the mootability and emotional stability factors have significant correlations with many JI-R scales, followed by Extroversion.