Many graduates of a master of political science will have a career as a policy professionals: working as political advisor, civil servant or consultant or policy analyst. Policy professionals can have a considerable impact on policy decisions. When preparing political decisions, for example, they determine the menu of choice. When implementing political decisions, they can use front-line discretion to align these decisions with their preferences. In this course, we study the role of policy professionals in political-decision making. The first two weeks will consist of theoretical sessions that provide us with a frame of reference to discuss the role of policy professionals in politics. The following six weeks, we will discuss concrete cases of policy making. In all the cases, policy professionals have an important role to play. The cases are very diverse: The Flint (Michigan) lead poisoning scandal, the stress tests of the European Central Bank, the Smart city agenda, the refugee crisis, large infrastructure projects and front-line policing. The literature on the cases typically consists of a long read that introduces the case and a scientific text that helps to understand the cases and the role of policy professionals.