This is a book that grew out of frustration. The frustration was rooted in our failed attempts to help people modify health-related behavior. From a behavioral medicine perspective, it was readily apparent to us that there were many things people could do to improve their health. Some of these were preventive behaviors, whereas others were much more therapeutic or rehabilitative in nature. Put another way, there were specific well-known behavioral strategies that people could use to maintain or regain their good health. Yet despite our good intentions, enthusiasm, and considerable efforts, something was wrong. People dropped out of therapy or failed to follow behavioral prescriptions. Workshops and clinics were half-empty. If people would attend workshops or follow therapeutic programs, their health would benefit. Yet in our experience and in the experience of most of our colleagues, compliance to treatment programs was a major problem. Faced with such a situation, it is easy to blame the victim-in this case the client. It is common to hear therapists talk of poorly motivated clients, complain that people are just not interested in improving their health, or even speculate about people's self-destructive tendencies. Although this may be comforting to the thera pist, it does very little to solve the problem. What was needed was an approach to improve adherence to therapeutic programs rather than comforting excuses for their failure. It is in this context that we became exposed to the area of social marketing.