Up to 250 children and adolescents ages 5 to 18, meeting DSM IV criteria for schizophrenia, schizoaffective disorder, and psychotic disorder not otherwise specified, are currently under study in our group. The purpose of this protocol is to allow systematic outpatient, and subsequent inpatient, screening evaluation to establish an accurate diagnosis for research, obtain clinical and neurobiological research measurements, evaluate the patient s response to open treatment with antipsychotic(s), and allow longitudinal follow-up. Subjects and first-degree relatives may then be enrolled in Protocol 89-M-0006, Brain Imaging of Childhood Onset Psychiatric Disorders, Endocrine Disorders and Healthy Controls, and Protocol 84-M-0050, Biochemical, Physiological, and Psychological Measures in Normal Controls and Relatives of Psychiatric Patients. If additional research protocols are available, this screening protocol will represent an entry point for them.