It is a widely accepted view today that psychosocial factors can cause psychiatric disorders. However, this view has, as yet, no firm foundation of verifiable facts. This paper outlines some research strategies that can provide data in favor of or against this theory: (1) systematic analysis of life events preceding psychiatric disorders, covering both stable events and interactional events; (2) vulnerability research on three levels (biologic, psychological, and sociological), aimed at factors that could explain the increased vulnerability of some individuals to the detrimental effects of life events; (3) pathogenesis research, aimed at analyzing how psychosocial stress disrupts cerebral systems, and discovering which of these disruptions is responsible for disturbed behavior, and (4) research into the efficacy of combined biologic (mainly pharmacotherapeutic) and psycho(socio)therapeutic methods. Some results obtained in these areas of research are discussed. The central idea of this study is that psychosocial and biologic factors do not operate independently but in close interaction. This seems a cliché, but is not, as clearly indicated by the scantiness of relevant research so far carried out. This gap is to be filled if psychiatry is to maintain and reinforce its status as a medical discipline. © 1979.