This paper is concerned with the appropriateness of current attempts to prevent chronic disease through behavioural change. Based on extensive ethnographic research in South Wales, the paper suggests that, within contemporary British health culture, there exists a well developed lay epidemiology which has a significant bearing on the public plausibility of modern health promotion messages. The paper describes the notion of the coronary candidate (the ‘kind of person who gets heart trouble’) and discusses the operation of the idea in everyday life. The manner by which lay epidemiology and the population approach to health promotion construct the ‘prevention paradox’ within the social world is outlined. In conclusion it is suggested that lay epidemiology readily accommodates official messages concerning behavioural risks within the important cultural fields of luck, fate and destiny. This simultaneously constitutes a rational way of incorporating potentially troublesome information, and a potential barrier to the aims of health education.