Participants in this study will be admitted to the NIH Clinical Center for up to 9 weeks under one or more of the following conditions: current medication, no medication, or tapered medication. Participants will undergo blood, urine, metabolic, and intellectual functioning tests. An electrocardiogram (EKG) and electroencephalogram (EEG) will be performed. A magnetic resonance imaging (MRI) scan of the brain will be taken and infrared oculography will be used to measure eye movements. Participants and their family members may also be asked to participate in a study of genetics in children with psychotic illnesses. Children meeting criteria for childhood onset schizophrenia may be offered participation in a medication comparison protocol.