The paper discusses the role of uncertainty in economic sociology, aiming to clarify some controversial issues in the related literature. Initially,some conceptual remarks are made about the relation between economic sociology, neoclassical economics, and rational choice theory. Next, in light of the existing literature on uncertainty and economic sociology, we distinguish between complexity and different types of uncertainty. We also identify different versions of the maximization hypothesis and examine their relations to the different types of uncertainty. Then we defend a concept of fundamental uncertainty that emphasizes the role of institutions. A theory that combines fundamental uncertainty and institutions should emphasize not only the existence of behavior in accordance with institutions, but also the possibility of creative, bold, unconventional behavior, discussed next, as people may use the knowledge provided by institutions to go against the tide. Finally, we suggest that the primary distinction should be that between approaches to economic issues, not between disciplines.