In a prospective longitudinal study of children of severely schizophrenic mothers, premorbid behavioral data on individuals diagnosed as suffering from schizophrenia spectrum disorder were compared with the same data on individuals diagnosed as not suffering from any mental disorder. Future schizophrenia spectrum individuals were passive babies who exhibited short attention spans. In school, they experienced interpersonal difficulties and displayed disturbing behavior, reflecting poor affective control. From clinical assessments at a mean of 15 years of age, formal cognitive disturbance and defective emotional rapport emerged as premorbid characteristics of schizophrenia spectrum disorder. These results seem to indicate that signs of defective emotional contact and formal thought disorder are important for the psychopathology of schizophrenia. Furthermore, the premorbid similarity of borderline schizophrenia and schizophrenia suggests a basic relationship between these two disorders.