One of several possible diagnostic perceptanalytic formulæ deducible from a statement about the etiological difference in kind (and not merely of degree) between psychoneurosis and schizophrenia has been developed and applied to a group of followed and not followed patients. This alpha formula differentiated between these 2 mental disorders to a high degree. However, it is applicable only in about one-third of schizophrenic cases. Four additional differentiating criteria have been devised to aid in the differential diagnosis between schizophrenia and organic cerebral disease.Abstract Teaser