An ideal model for clinical preventive care must consider the physician, the patient and the many factors which influence each of them. In this paper, we review existing models, examining their strengths and weaknesses. We then propose a new model, the Systems Model of Clinical Preventive Care. This model is unique in its focus on the patient-physician interaction and details the factors impinging on each that promote or inhibit the completion of preventive care activities. These factors include patient and physician predisposing factors, such as health beliefs and attitudes; enabling factors, such as skills and resources; and reinforcing factors, such as social support. Additional factors include health care system organizational factors, such as access or availability; characteristics of the preventive activity, such as cost; and cues to action, such as symptoms or reminders. The proposed model contains components of behavioral, communication, health education and psychosocial theories. We then apply our model to mammography as an example of a screening activity. Finally, we describe the strengths and weaknesses of the proposed model, and identify areas for future research.