In a preliminary study of developmental precursors of schizophrenia, home movies of adult-onset schizophrenic patients and their healthy siblings filmed during their childhood were viewed by judges who were blind to the psychiatric outcome of the subjects. The films began with the infancy of all subjects and extended through at least the first 5 years of their lives. Although none of the subjects had any psychiatric disorder in childhood, the preschizophrenic children were reliably identified by the viewers. This represents the first demonstration that preschizophrenic subjects can be distinguished from sibling control subjects within the first 8 years of life by observing their behavior.