During this era of health promotion and disease prevention, interest in health behavior change has never been greater. For example, interventions are being developed to prevent the occurrence of chronic disease through efforts aimed at reducing cholesterol, blood pressure, body weight and smoking-related behaviours. Other programmes are aimed at improving, through behavioural interventions, the health outcomes of patients with a variety of existing chronic conditions, including asthma, diabetes, arthritis and coronary heart disease. Still other programmes are being designed to encourage the public to enroll and participate fully in screening programmes for cancer prevention (e.g. mammography and Pap tests), as well as for other preventive clinical services, including immunisations. Previously, behavioural interventions were usually considered to be the stepchild of medical treatment and clinical interventions; now, behavior change strategies are often considered to be the “action of choice” for the prevention and control of many acute and chronic conditions. One need only look at the global efforts to control AIDS to understand the significant role that behavior change strategies are currently playing and their potential for future applications.