International Organization is a quarterly peer-reviewed academic journal that covers the entire field of international affairs. It was established in 1947 and is published by Cambridge University Press on behalf of the International Organization Foundation. The editors-in-chief are Brett Ashley Leeds and Layna Mosley.
International Organization is considered the leading journal in the field of international relations, and one of the top journals in political science. In a 2005 survey of international relations scholars on "which journals publish articles that have the greatest impact" in their field, about 70% included International Organization among the 4 "top journals", ranking it first among 28 journals. According to the Journal Citation Reports, the journal has a 2022 impact factor of 7.8, ranking it 3rd out of 187 journals in the category "Political Science" and 1st out of 96 journals in the category "International Relations".