Recent theory in anthropology has increasingly been concerned with issues of power. Anthropology also has a long history of interest in variation in cultural knowledge, which, we argue, benefits from attention to power relations. To show this, we examine perceptions of breast cancer risk factors among physicians. Although physicians share a general cultural model of breast cancer risk factors, variation exists, especially between university-based physicians and community-based physicians. The nature of the work performed in these two settings influences the acquisition of various sources of information and frames what is considered valid information. Similar to Foucault's argument, we find that physicians working in a university setting are more disciplined in discussing their perceptions of breast cancer risk factors, compared to community-based physicians, who move away from the centers of knowledge and power (universities).