In the late 1940s, postcolonial elites expanded the activities of the United Nations (UN) by using it as a platform to advance decolonization and foster Third World solidarity. The Arab-Asian group was the earliest manifestation of institutional cooperation among postcolonial nations after 1945. Initially comprised of twelve Arab and Asian UN member-states, the Arab-Asian group coordinated their diplomatic activities as part of an effort to bring national self-determination to the forefront of international debate. However, the emergence of the Arab-Asian group at the UN revealed a confluence of different political ideologies and approaches to decolonization in the early postwar era. Forging a network of postcolonial elites brought out divergent visions for the postwar international order, illustrated by the frictions within the Arab-Asian group even as it played key roles in the UN debates on the questions of Indonesia, the former Italian colonies in Africa, and the Korean War. The Arab-Asian group, an important antecedent to Afro-Asianism, Third Worldism, and non-alignment, encountered challenges over parallel projects pursued by its members, such as Carlos Romulo’s campaign for a Pacific Pact among non-communist Asian states or Jawaharlal Nehru’s articulation of neutralism. Therefore, while postwar international organizations were a formative setting for the emergence of postcolonial internationalism and South-South solidarity, the common goals pursued by these states did not always translate into uniformity or consensus on decolonization.