The development of school-age children born to parents with serious mental disorders was assessed on a variety of perceptual-cognitive and motoric tasks. These same children have been followed up from birth as part of the Jerusalem Infant Development Study. Children with schizophrenic parents, when compared with children with healthy parents or parents having other psychiatric disorders, were more likely to show neurobehavioral dysfunctioning in perceptual-cognitive and motoric areas. Forty-four percent of the offspring of schizophrenics (11 of 25 subjects) showed such dysfunctioning. Male subjects were overrepresented in this poorly functioning group. A stable subgroup (40%) of the offspring of schizophrenics (six of 15 subjects) showed dysfunctioning during infancy and school age. None of the offspring of nonschizophrenic parents showed dysfunctioning during both age periods. While most of the poorly functioning children with schizophrenic parents showed perceptual-cognitive and motoric signs, only perceptual-cognitive signs were strongly linked to parental diagnosis and infant dysfunctioning. Motoric signs, but not cognitive signs, were related to pregnancy and birth complications. These findings provide further support to the schizotaxia hypothesis that some neurointegrative deficits may reflect vulnerability to schizophrenia and that these deficits are clearly apparent at school age, long before the onset of illness. However, these signs are not exclusive to schizophrenic illness, although they occur with a greater prevalence in this group. Definitive statements about the validity of early neurobehavioral signs as indicators of genetic vulnerability await further longitudinal follow-up into the age of risk for actual schizophrenic breakdown or when a diagnosis of schizotypal personality disorder may be made.