In this paper we argue that evidence-based practice, which is being introduced throughout the British National Health Service to make decisions about the allocation of limited resources, provides a welcome opportunity for health visitors to demonstrate their efficacy, skills and professionalism. However, the paper argues that to view health visiting as evidence-based is not to reduce health visiting merely to a technology through which scientific solutions are applied to social problems. Rather, health visiting needs to be viewed as a political movement, based on a particular model of society, which shapes the goals which health visitors pursue and influences the strategies they adopt to achieve their goals. The paper describes various models of health visiting as a way of showing how the goals of health visiting are always framed within a particular set of assumptions and causal explanations. The paper then turns to look at the issue of evaluating health visiting services. It is argued that evaluation should properly take account of the models which shape health visitors' goals and intervention strategies, and in turn, health visitors need to be explicit about the theoretical frameworks underpinning their interventions. Finally, it is argued that health visitors' knowledge and understanding of a range of models of society enables them to move between the various models to choose the most appropriate and effective means of intervention. Hence it is concluded that the emphasis on evidence-based practice provides health visitors with a valuable opportunity to show that their unique, professional skills and understanding are the preconditions for effective intervention.