The multiplicity of forms of health-related knowledge, including biomedical knowledge, lay knowledge and critical constructionist knowledge, raises challenges for health researchers. On one hand, there is a demand for a pluralist acceptance of the variety of health-related knowledge. On the other, the need to improve health calls for action, and thus for choices between opposing forms of knowledge. The present article proposes a pragmatist approach to this epistemological problem. According to pragmatism, knowledge is a tool for action and as such it should be evaluated according to whether it serves our desired interests. We identify implications for research methodology and the choice of research goals.