It was the aim of the study: to compare the behavioral and cognitive effects of pharmacological and behavioral therapies in the short-term, clinical treatment of minimal brain dysfunction; and, to compare the behavioral and cognitive effects of stimulant (methylphenidate) and antidepressant (imipramine) drugs in the short-term, clinical treatment of minimal brain dysfunction. Twenty-nine boys, ranging in age from 6 through 12 years, with the diagnosis of minimal brain dysfunction with hyperactivity, were randomly assigned to three treatment groups: imipramine, methylphenidate, or behavior modification. The total time of treatment for each child was 6 weeks. For subjects within the imipramine and methylphenidate groups, medication dosage was individually titrated by a child psychiatrist. (Range: 75- 150 mg/daily of imipramine, 10- JO mg/daily of methylphenidate.) Parents of subjects within the behavior modification group individually met with an experimenter l hour per week. Behavioral principles were discussed, problem behaviors targeted, and behavioral programs devised for implementation during the treatment period. Subjects assigned to behavior modification were also individually seen once weekly. The first part of a session focused on behavioral control, following the method of behavior rehearsal. Working from problem areas targeted by parents, the subjects and experimenter discussed specific encounters, and then reenacted these incidents, rehearsing alternative, adaptive behaviors. The second part of a session was devoted to cognitive control, with training in self-directed verbal commands instituted. On tasks of trail making, matching pictures, and embedded figures, subjects verbally cued themselves to delay and to consider requirements before attempting a solution, with reinforcement contingent upon responses correct on initial trial. For all groups, prior to and following treatment, behavioral and cognitive measures were obtained: parents completed a behavior rating scale, the Parent's Questionnaire; teachers completed the School Report, assessing behavior and academic achievement; and subjects were administered a battery of psychological tests which included the Wechsler Intelligence Scale for Children, Wide Range Achievement Test, Porteus Maze Test, Bender Gestalt Test, Developmental Test of Visual-Motor Integration, and Draw-APerson. Analysis of the data from teachers' global ratings of behavior indicated the superiority of pharmacological treatment in comparison with behavioral treatment. Within the cognitive area, based on teachers' global ratings of academic achievement and the Porteus Maze Test, pharmacological treatment was again shown superior. Isolating specific group effects, contributing to the major portion of the variance between pharmacological and behavioral treatments was the superiority of methylphenidate to behavior modification. Further research was felt necessary concerning the therapeutic comparability or lack of comparability of imipramine and behavior modification treatments. Between imipramine and methylphenidate treatments, based on teachers' ratings of hyperactivity and global ratings of both behavior and academic achievement, differential effects, in favor of methylphenidate, were suggested. Thus, the comparability of imipramine and methylphenidate treatments in terms of both behavioral and cognitive effects was felt to be in question. Results were discussed in terms of the bounds of the design, procedure, and measurements. Qualifications were noted concerning statistical power, Type I error, the relative rather than absolute efficacy of the treatments, and the validity of the measurements. Application and research implications were presented. The need for continued research into the application of behavioral programs with MBD children, both independent of and in conjunction with pharmacological treatment, was stressed, with suggestions provided as to the clinic-based and, to a limited extent, school-based implementation of such programs.