Abstract
In an attempt to test hypotheses derived from Mahler's theory of borderline development, Rorschach protocols of borderline and schizophrenic patients were studied for the presence of themes related to the separation-individuation process. A specially constructed Separation-individuation Theme Scale was used with a 96% reliability of agreement between two raters. The borderline group attained more separation-individuation themes than the schizophrenic group, whereas the schizophrenics showed more preseparation-individuation themes. The results were interpreted as a validation of Mahler's theory. In addition, the results tended to confirm a developmental model for the understanding of psychopathology.