Breast cancer is the leading cause of death among women 15 to 54, and it will strike one in ten American women. Early detection provides the best chance for successful treatment and survival. The American Cancer Society recommends monthly breast self- examination (BSE) for women 20 years and older as a major component of an effective early detection program. Although easy to learn and requiring minimal time investment, the vast majority of women fail to comply with recommendations for monthly BSE. Facilitation of BSE compliance can be approached from several directions. One possible focus is on the consequences of BSE for the women engaging in it and their effect on subsequent performance. One of the basic psychological principles is that a behavior that is reinforced is more likely to occur again. Performance of BSE has no intrinsic reward (the optimal result is to find nothing), and, in fact, it may be punished (by the experience of negative emotions, e.g., anxiety, that accompanies it). Thus, developing methods of operating on the environment which enhance positive reinforcement of the practice of BSE appears to be a useful direction in which to proceed. The proposed project will test the hypotheses that college women who are reinforced for performing BSE will be more likely to continue to practice it than similar women who receive no reinforcement, and that peer-delivered reinforcement will be more effective than self-delivered reinforcement. Women will attend workshops where they will learn proper BSE technique and will be asked to do monthly BSE for a nine month reporting period. One group will sign a contract with the experimenter to provide themselves a specified reward following each BSE, a second group will sign a contract with the experimenter and a "buddy" who will provide the reward, and a third group won't be reinforced. At the end of the 9-month period, the compliance rates among groups will be compared.