Twenty hyperactive 6- to 9-year-old children of normal intelligence were studied in a half-day laboratory classroom in a 2-week period baseline-treatment-reversal design for behavior modification. Under double-blind conditions half the children were placed on .3 mg/kg of Ritalin and half on placebo for the entire program. The classroom program consisted of a group period with immediate reinforcement possible, and an individual time period without immediate reinforcement possible. Behavior modification caused a significant decrease in nonattending, out-of-seat, inappropriate vocalizing and inappropriate peer interaction behavior in the group period. Fidgeting, a nontargeted behavior, was not significantly decreased during this period but did significantly decrease as a result of medication. No other drug effects occurred during this period. During the individual period, the results were essentially reversed. There were no significant behavior modification effects observed. Significant reductions resulted from medication in all behaviors except out-of-seat and fidgeting. Behavior modification alone significantly affected the two academic measures. No signigicant effects were seen on the Conners Abbreviated Teacher Rating Scale. No significant interactions were noted between medication and behavior modification.