This aim of this clinical trial was to study the effects of divalproex sodium (DVPX) in reducing Reactive/Affective/ Defensive/ Impulsive Aggression (RADI) in youth with Disruptive Behavior Disorders (DBD) in an outpatient clinic over a period of 3 months. We recruited forty participants with Oppositional Defiant Disorder or Conduct Disorder. Twenty participants received 12 weeks of openly titrated DVPX, whereas twenty participants served as a comparison control group. Primary efficacy measures were the Clinical Global Improvement-Severity (CGI-S) and CGI-C (Change) scales; secondary efficacy measures included standardized measures of aggression. Based on the CGI-S and CGI-C ratings, the DVPX group showed significant improvement by the last observation. Attrition rates were notably high, which is not surprising given the clinical population studied. This study provides further support for the efficacy of DVPX in decreasing RADI aggression in the context of DBD. These results are particularly noteworthy because the sociotherapeutic structures supporting patients in previous trials were not present.