We are requesting 5 years of support for a study of brain lateralization in adolescent psychosis. The psychotic disorders in adolescents are not well understood scientifically or clinically, and the etiology, prognosis, and optimal treatments for psychosis in adolescents remain uncertain. Adolescents are underrepresented in biologically oriented neuropsychiatric research, especially within the context of recently developed functional and structural brain imaging metrics that have shown promise in our improved understanding of psychoses in adults. We are proposing a formal study of adolescent onset psychoses implementing certain of the new non-invasive metrics that have shown significant promise to improve our understanding of disease process in adults with psychotic disorders, including magnetoencephalography (MEG) functional measures, and magnetic resonance imaging (MRI) structural measures. in adults with psychotic disorders, we have published MEG and magnetic source imaging (MSI) measures of anomalous structural and functional lateralization of the brain. These findings appear to vary with the presence or absence of psychosis across several major neuropsychiatric disorders, and there is some suggestion that the specific patterns of anomalous lateralization may differentiate these disorders from one another. Such abnormalities, if present in adolescents with early onset, undifferentiated psychosis, may contribute to 1 ) earlier and more accurate diagnosis, 2) improved treatment planning at onset of illness, 3) more accurate estimate of illness trajectory and prognosis, as well as future family studies of the genetics of brain lateralization.