<qa>  What is the dose of the study medication?This phase will last 4 weeks. Subjects that meet inclusion criteria will be randomized to receive study medication risperidone or placebo as augmenting treatment to stimulant medication. The dose of the stimulant will remain constant during this phase. Janssen Pharmaceutica will supply risperidone 0.5 mg and identical placebos. All research staff and subjects will be blind as to the study medication to be administered. The dose of the study medication will be started at 0.5 mgday. The dose for each child will be individually regulated until optimum efficacy or until the side effects become unacceptable. The guiding principle will be to achieve control of symptoms with the lowest possible dose in order to minimize undue side effects. The medication dose can be gradually increased by 0.5mg weekly to a maximum of 2 mgday. Dose reduction for adverse events may occur at any time and be made in any multiple of 0.5 mg as deemed clinically necessary. No other concomitant medication will be permitted. Subjects will attend the research clinic on a weekly basis for behavioral assessments and medication distribution. 