After it is determined that a child is eligible to participate, there will be a baseline visit. The child's previous ineffective medication will be discontinued. The ratings done at the first visit will be repeated, including both the teacher and parent rating scales. The child will have vital signs taken including height, weight, blood pressure and pulse rate, an electrocardiogram (EKG) (a test of heart rhythm recorded by putting sticky pads on the chest), a urine test and a blood test (about 10cc or 1 tablespoon). The doctor will ask the parents about the child's medical history. Parents will be told about any abnormal laboratory values or physical findings that may be discovered during this study. This information will also be available to the child's pediatrician if the parents request this be done.