IN RECENT YEARS psychiatrists have come to realize that psychological maldevelopment, maladaptation, and illness are so prevalent that treatment of established cases can never be expected to deal adequately with more than a fraction of the cases which occur. Therefore, one must consider how to reduce the incidence of mental illness, as well as to promote mental health. Primary prevention is that preventive effort which is concerned with studying the populationwide patterns of forces influencing the lives of people in order to learn how to reduce the risk of mental disorder. Although we currently have little definite knowledge of the specific factors which are etiologic in specific mental diseases, there exists a body of plausible assumptions about various factors which may be significant in primary prevention. Some of these assumptions are based on experiments on human beings and animals, others are inferred from theory. Some are based