Behaviour change is an important concept in relation to health promotion and disease prevention. Self-efficacy has been identified as an important determinant of health behaviour, future health behaviour and health behaviour change. In order to effectively facilitate behaviour change, it is essential that interventions are research based, and emphasize the utility of theory in practice. The effective practice of health promotion and disease prevention requires a full understanding of the processes of patient behaviour. This article presents the role of the nurse in influencing health-related behaviour change. Self-efficacy and related but distinct theories that underpin behaviour change are discussed. The empirical evidence that supports the link between self-efficacy and predictions of health behaviours is also examined.