Social science research into the social patterning of health and illness is extensive. One important aspect of this has been work on lay knowledge about health and illness. In this paper we develop three main arguments. First, we suggest that recent developments in social science understanding of the nature and significance of lay knowledge should be more widely recognized within the social sciences themselves. Second, we argue that if public health research, whatever the disciplinary perspective, is to provide an understanding of contemporary health problems that is simultaneously more robust and more holistic, it must incorporate and develop the theoretical and conceptual insights offered by this recent work on lay knowledge and with lay people. Finally, we argue that in order to accomplish this it will be necessary to construct research questions in such a way that the conventional distinctions between science and non-science, and the methodological wrangles associated with this distinction, become marginal to the research process. This will inevitably involve conflicts between members of different professional groups. These conflicts provide the opportunity for open debate on the science and politics of public health research and represent a challenge for the many disciplines involved in this field.