Politicians need expertise to make public policies, and civil servants are principal and proximate providers of knowledge. Yet, what constitutes relevant knowledge and skills for bureaucrats is... Show morePoliticians need expertise to make public policies, and civil servants are principal and proximate providers of knowledge. Yet, what constitutes relevant knowledge and skills for bureaucrats is regularly contested—both by politicians and bureaucrats—and subject to change. How can we explain the processes of contestation and change in the expertise of policy bureaucracies? The article presents a theoretical framework for analyzing the politics of bureaucratic expertise. It proposes the concept of “expertise bargains” to capture the understanding between politicians and bureaucrats about the knowledge and skills of civil servants. Based on a transactional view of authority in bureaucratic politics, it argues that the terms of this expertise bargain are mutually defined by politicians and bureaucrats through a dynamic bargaining process. The analytical utility of the framework is demonstrated through a comparative-historical analysis of contestation and change in bureaucratic expertise in the field of economic policy. Show less