This study of hyperactive boys evaluated the effects of three modes of treatment in relation to an untreated group. The treatments were administered over a 3-month period and included cognitive training, stimulant drug therapy (methylphenidate), and the two treatments combined. A follow-up assessment was conducted approximately 3 months after contact between the training staff and the child had ceased. Analyses of attentional deployment and cognitive style measures, tests of academic achievement, and behavioral ratings showed that only those children in the two medication treatment conditions demonstrated improvement in attentional deployment and behavioral ratings. In the cognitive therapy condition, there were changes only on measures of attentional deployment. The data did not provide evidence indicating that the combined medication and cognitive therapy condition was any more effective than that condition involving medication alone. Discussion provides future guidelines for evaluation of the relative effectiveness of stimulant drug therapy and other psychological treatment modalities.