Approaching international organizations (IOs) as political systems, this excellent textbook offers a unique entry point to the study of multilateralism. Guided by the most pertinent theories, it elucidates in a highly accessible style how IOs are created, how they shape global politics, and what problems they encounter in this process. The outstanding fourth edition of International Organization provides important empirical updates, widens the spectrum of covered policy fields, and anchors the book in the most recent academic debates. A must-read for anyone interested in IOs and global governance.