This paper explores interactions between ecological science and conservation values in the biodiversity-ecosystem function debate of the 1990–2000s. The scientific debate concerned the interpretation of observed correlations between species richness and ecosystem properties like primary productivity in experimental ecosystems. The debate over the causal or explanatory role of species richness was presumed to have implications for conservation policy, and the use of such research to support policy recommendations generated hostility between rival groups of ecologists. I argue that the debate was (...) due in part to the adoption of a broad conception of biodiversity as a goal and value in conservation politics and ethical debates, and the ecologists who questioned the causal efficacy of species richness were also suggesting problems with this goal. I characterize what I call the “uneasy consensus” established by BEF researchers in the late 2000s, discuss roles for values in BEF research, and suggest that this episode shows that ecological science can itself be an important site for ethical debates about conservation values. (shrink)