The historical development of the mental health clinic's interest in crime prevention is outlined, followed by an assessment of the current state of mental health programs and research focusing on crime prevention. This assessment discusses prevention versus treatment, the imbalance between the relatively heavy concern with preventing juvenile crime compared to the concern for adult crime prevention, and the little attention given to preventing female criminality. A model is described which is designed to classify mental health patients with symptoms of being potential offenders, so they may be given priority for preventive treatment. Prevention programs are described in the areas of diagnosis, types of personnel used, and youth projects. The discussion of preventive diagnosis includes consideration of the hand test, Briston Social Adjustment Guides, the Glueck Social Prediction Table, medico-biological techniques, and diagnosis through family examination. Personnel considered for use in mental health prevention programs include inmates, nonprofessional mental health volunteers for the community, the use of health aides, and retired nonprofessionals. The youth projects described are the day-hospital service in a child guidance clinic and the Cambridge-Somerville Youth Study. Prevention programs considered in the concluding chapter focus on drug addiction, psychotherapy and medication, alcohol abuse. Recommendations are offered for improving research and treatment relating to crime prevention. A bibliography with 173 listings is provided.