This review is a clinical and research update of recent literature related to childhood onset schizophrenia (with an onset of psychosis by age 12). Childhood onset schizophrenia(COS) is a rare disorder, but that may represent a more homogeneous patient population in which to search for risk or etiologic factors of schizophrenia. These overview data show that COS shares the same clinical and neurobiological features as later onset forms of the disorder. Compared with later onset schizophrenia, however, this subgroup of patients appear to have more severe premorbid neurodevelopmental abnormalities, more cytogenic abnormalies, poor outcome, and potentially greater family histories of schizophrenia and associated spectrum disorders. Future studies of this subgroup may provide important clues as to the genetic basis for schizophrenia and how gene products influence certain feature of the disease, such as age of onset and mode of inheritance.