The program consists of three research projects. I. The relative efficacy of methylphenidate, behavior modification, and the combination of methylphenidate and behavior modification is being investigated in non-psychotic hyperactive children of normal IQ, between the ages of 6 to 12. Treatment lasts 12 weeks. Results so far indicate that methylphenidate treatment is significantly superior to behavior therapy. No significant advantage has been found so far for the combined use of methylphenidate and behavior modification over medication alone. II. The purpose of the study is to determine the value of methylphenidate combined with remediation techniques in children with learning disabilities. Subjects consist of children, between the ages of 6 to 12, with normal IQ's, who have been referred because of academic difficulties, who score significantly below grade level on individually administered reading tests. Experimental treatments consist of reading remediation with placebo, reading remediation with methylphenidate, and academic tutoring with placebo. The latter group receives tutoring in school subjects, but not in reading per se. All remediation is individual, for 54 sessions over a 4 month period. III. The project is a prospective clinical long-term follow-up of 200 hyperactive children being treated with stimulants. The children's social, academic and psychometric characteristics are evaluated over time. In addition, the children's height and weight is being monitored.