The participants were referred for diagnosis and treatment of ADHD to a large urban teaching hospital. They were ages 5-17 and were matched for age, sex, and diagnostic subtype. Each group included 33 males and 9 females. The prescribing physician assigned each participant to a treatment group. Participants were all evaluated under five conditions, including baseline, placebo, 5 milligrams, 10 milligrams, and 15 milligrams. The best dose was assigned prior to breaking the medication blind and was assigned by the consensus of the psychologist and psychiatrist. Subjective ratings by both teachers and parents were examined for the dosage-level effects and the medication-type effects. Results revealed that the best dose was always superior to the baseline and placebo conditions. In addition, teacher and parent ratings of behavior revealed no differences between the two trust. Both medications appear to improve teachers' and parents' ratings of behavior. The single-dose treatments of Adderall appear to be as effective as two daily doses of methylphenidate and therefore increase the possibility of managing treatment without involving the school in administering medication. In addition, youths who previously have been unsuccessfully treated with methylphenidate due to adverse side effects or poor response may be successfully treated with Adderall. Tables and 13 references (Author abstract modified)