This article discusses theoretical approaches that have led the study of international organization, including the United Nations (UN), for the last fifty years. It explores how analysts have conceived the ways that the UN not only regulates the existing activities of states, but also helps weave the fabric of international society. It clarifies the different schools of thought that were developed throughout the twentieth century to help understand the behaviour and misbehaviour of international institutions. The article concludes by asking scholars to work harder in understanding influence within intergovernmental organizations, otherwise known as the first, second, and third UN.