OBJECTIVE To evaluate reliability and validity for the Neuropsychiatric Rating Schedule (NPRS) interview designed to permit diagnosis of organic personality syndrome (OPS) or personality change due to a general medical condition (PC). METHODS Subjects from prospective (n = 50) and retrospective (n = 72) studies of traumatic brain injury were aged 6 through 18 years. Parents and children were informants for the NPRS. Convergent and discriminant validity of subtypes of OPS/PC were assessed against standard scales completed by parents and teachers. Interrater reliability data (n = 20), test-retest reliability data (n = 42), as well as sensitivity-to-change data (n = 37) were collected. RESULTS All subtypes of OPS/PC were diagnosed, but apathy and paranoia subtypes were rare. Rating scale data supported convergent validity of OPS/PC subtypes generated with the NPRS. Affective instability, rage/aggression, and inappropriate social judgment were moderately to highly correlated, but apathy and paranoia could be discriminated from each of these subtypes. Interrater agreement for NPRS items was fair to excellent for all but one item (paranoia). Test-retest reliability was fair to good, and sensitivity to change was demonstrated. CONCLUSIONS The NPRS generated reliable and valid diagnoses of the common subtypes of OPS/PC.