Following the first injection, subjects will return to the study center for weekly visits for 8 weeks. At each study visit, patients will be evaluated for possible adverse events, use of concomitant medications, and use of methamphetamine. Safety labs will be repeated at week 4 and 8. Plasma levels of risperidone and 9-OH-risperidone will be obtained at 3, 6, and 8 weeks. If intolerable adverse events occur, risperidone dosage will be reduced, or, if indicated, risperidone will be discontinued. Psychiatric symptoms and cognitive functioning will be evaluated at Baseline, and 4 and 8 weeks. A follow-up visit will take place at 12 weeks. Subjects will receive behavioral treatment consisting of individual, once weekly, standardized, manual guided, relapse prevention therapy.