There appears to be a practical, but also an ideological, difference between the professional activities of disease prevention and health promotion. Whether or not this distinction holds has to do with at least two things. First, it has to do with the concept of health and the concept of disease. Are they logically different (and only causally related), or are they just two extremes on one dimension? Second, it has to do with the practices of professionals. Are the methods and strategies used in health promotion different from those used in disease prevention, and are the targets, e.g. the whole population, sub-populations, communities, risk groups, of these methods and strategies different? In the paper it is argued that the difference is much smaller than is sometimes assumed. First a conceptual framework is suggested, where the concepts of health, illness and disease are defined, and it is shown that it does not follow logically from these definitions that disease prevention and health promotion require different methods and strategies. Then it is shown that differences in choice of target for interventions have other reasons, e.g. professional affiliation and ethical assumptions.