This article develops a preventive health paradigm for health care psychologists by building on public health and preventive mental health models of primary, secondary, and tertiary prevention. Adoption of a "biopsychosocial" perspective on health and illness is basic to the preventive health paradigm. Examples of preventive health programs are considered along with a wide range of preventive health activities by psychologists in health care settings.As psychology's identity as a health science and profession emerges, new opportunities, challenges, and mandates arise. As behavioral scientists and mental health practitioners, psychologists are in a unique position to understand and affect health and illness and medical utilization related to psychosocial or behavioral factors. Such activities are described as preventive health. The present article articulates a rationale for such activities by psychologists by building on public health and preventive mental health models of primary, secondary, and tertiary prevention. Examples of preventive health programs are presented.The emergence of psychology as a health science and profession is fueled by at least two major influences. One influence is the progress of behavioral, medical, and public health science. Another influence is the sociopolitical forces in the American health care crisis. The progress of science has necessitated reconceptualizations of classical mind-body problems and physical health-mental health dichotomies. Recent integrations such as the new medical model (Engel, 1977) and the new psychosomatic model (Lipowski, 1977) represent important advances in comprehensive ecological perspectives on health and illness as "biopsychosocial" phenomena. The recent birth or recognition of the new fields of behavioral medicine (Schwartz & Weiss, 1978a, 1978b and pediatric psychology (Wright, Schaefer, & Solomons, 1979), and the new Division 38 of the American Psychological Association, "Health Psychology," are further manifestations of important development.Interwoven with this progress in science are some major sociopolitical forces that make up the crisis in health care in American society. The runaway cost of health care and the movement toward national health insurance are controversial political issues that require the attention of psychologists, both because potential solutions will greatly affect psychologists and because contributions to these solutions are reasonably expected from psychologists. The former issue is exemplified by the problem of