A technique for clarifying the role of experiential factors in psychopathology-the crossfostering technique-employs the strategy of using adopted-away offspring of normal biological parents who are reared by schizophrenic parents. This group is compared with the adopted-away offspring of normal biological parents reared by normal adopting parents and the adopted-away offspring of schizophrenic biological parents reared by normal adopting parents. Analyses of psychopathology in these adoptees reveals that there is a greater prevalence of psychopathology among the adopted-away offspring of schizophrenics while no such increase is seen among the crossfostered group. The tentative conclusion of the study is that genetic factors play a role in the etiology of the schizophrenias while familial psychopathology (as measured by psychiatric diagnosis of the parents) does not. The possible roles of extrafamilial biological and psychological experience are considered.