Recently, two seemingly divergent approaches have emerged in outcomes-based medical research. Proponents of evidence-based medicine (EBM) argue that the most effective treatments will be found by adopting a hierarchical approach that gives pre-eminence to randomized controlled clinical trials, where these are available. Proponents of participatory medical research argue that research undertaken with consumers and other partners in the community will produce the best outcomes. While one approach marginalizes consumer experience the other approach draws consumers into it. EBM assumes a high level of consensus in a scientific community, while participatory medical research relies on co-opting consumer experience. This paper indicates that each approach involves a particular view of social structure in science. The paper uses theories of social relations among scientists for the purpose of critically assessing EBM and the participatory model.