The role of international institutions is central to the functioning of the international system after the end of the Cold war and of bipolarity, which inhibited cooperation among states. International relations' literature offers various points of view on the subject. Among the most important are neorealism, which is skeptical on the utility of institutions, and institutionalism, which positions them at centre stage. This essay will examine the basis of conflict and cooperation for institutionalism, in order to specify the role of institutions in such context. The neorealist critique to this argument will then be analyzed, in conjunction with the different conception of institution which follows. Finally, the advantages and disadvantages of a recent attempt at merging the two views will be be discussed, with reference to the explanation of the relevance of international institutions in the contemporary world.