Epistemological differences fuel continuous and frequently divisive debates in the social sciences and the humanities. Sociologists have yet to consider how such differences affect peer evaluation. The empirical literature has studied distributive fairness, but neglected how epistemological differences affect perception of fairness in decision making. The normative literature suggests that evaluators should overcome their epistemological differences by ‘‘translating’’ their preferred standards into general criteria of evaluation. However, little is known about how procedural fairness actually operates. Drawing on eighty-one interviews with panelists serving on five multidisciplinary fellowship competitions in the social sciences and the humanities, we show that (1) Evaluators generally draw on four epistemological styles to make arguments in favor of and against proposals. These are the constructivist, comprehensive, positivist, and utilitarian styles; and (2) Peer reviewers define a fair decision-making process as one in which panelists engage in ‘‘cognitive contextualization,’’ that is, use epistemological styles most appropriate to the field or discipline of the proposal under review.