This paper shall set out to examine the role in which institutions play when influencing states actions on the global stage, but first we should understand what institutions are and where their prominence came from, and why they have not always been key actor on the global stage. In order to do as such this essay will first define what institutions are then look at what are the primary institutions that affect states actions in IR and focus on these as to not spread the goal of the papers objectives too thinly. It will then look at case studies and real life events where institutions have affected the behaviour of states for the better, this will mainly be focused on the role of international law and institutions such as the EC, international Energy Agency, EU, UN and NATO in addition to what power they can wield as to ‘keep states in line’ and acting in the interest and benefit of the many rather than the few. The penultimate part of this essay in order to keep a fair, balanced and holistic view of the role of institutions will be looking at the counter arguments and events of where they do not affect states on the global stage or fail to live up to their objectives, this will be based on the case study of how and why the United States of America acted with the global power in regards to the Iraq war as well as other cases where institutions are meant to block states acting against the international community and for their own gain, this paper will also address Mearsheimer’s criticisms of institutions. The finial part shall weigh up what this paper has covered and based on the arguments give a clear analysis of how affective institutions are, whether or not they do have a large impact on states and how they do this and if not how they can improve for future influence. Institutionalism can be defined as “a set of rules that stipulate the ways in which states should cooperate and compete with each other.” These rules once accepted by states tend to form international pacts or “mutual acceptance of higher norms.” Institutions emerged as primary actors on the global stage in the early 1990’s as the Cold War came to a close, in a post-Cold War era the world faced new issues that realism failed to effectively address. Before the end of the cold war Realism was straight forward and explained the world politics in simple terms with states as the main actors and balance of power politics the primary tool, when this ended Europe based policy makers wanted to strengthen security by empowering institutions as main actors on the global stage, Robert Keohane even stated that “institutions are key to maintain peace in Europe”. Institutionalism has three main components; Collective security, Liberal institutionalism, and Critical theory. Collective security is the concept that states bound tougher by force or circumstance whether it be regional such as NATO, political or other connecting points between them understand and accept that the