Studies on adult sexual aggressors have continuously demonstrated that the majority admit the onset of some form of sexual offending before 18 years of age. Although alcohol and drug abuse has been frequently associated with violent crimes in general, studies on alcohol and drug problems among adolescent sexual offenders have been seriously neglected. In truth, juvenile sexual offenders are a heterogeneous population, and some of them demonstrate profile characteristics similar to other nonsexual violent offenders. Research has shown that many adolescents who commit sexual crimes also perpetrate nonsexual offenses; thus, to draw a complete distinction between sexual aggressors and nonsexual offenders is a difficult task. In fact, the criminal versatility should be taken into account when sexual offenders in general are evaluated and treated. This study evaluates the alcohol and drug consumption, the impulsiveness levels and the dimensional aspects of personality between adolescent sexual aggressors who offended children and those who offended adults. Also, it verifies possible distinguishing psychological characteristics between those offenders who adhered or not to our treatment programme. The study was carried out by the Ambulatory for the Treatment of Sexual Disorder of ABC Medical School (ABSex). The offenders against adults showed more alcohol and drug problems than the group who offended children. In addition, the sexual offending behavior of the aggressors against adults showed to be one more facet of the opportunistic exploitation of others. Offenders against children revealed significantly fewer mean scores on “persistence” than aggressors against adults. Furthermore, there seems to be some different personality characteristics between the juvenile sexual offenders who adhere to the treatment in comparison with those that do not, mainly in terms of reward dependence and novelty seeking.