Why do states exit IOs? How often does IO exit happen? And what are the consequences of IO exit for leaving states? Despite recent attention to individual cases and the importance of membership in IOs, little is known about state exit from IOs across states, organizations, and time. Chapter 1 outlines the common logic of IO exit that links withdrawal and suspension: States often use IO exit as a strategy to negotiate institutional change when mechanisms of voice have failed. We summarize our empirical contributions that rely on a new dataset of IO exit across 198 states and 534 IOs from 1913 to 2022. We show that exit is infrequent, intermittent, and often temporary rather than terminal. Factors related to bargaining help predict IO exit, and exit generates negative reputational and cooperative consequences for leaving states. Nonetheless, IO exit is often an imperfect tool in achieving institutional change. Overall, we correct the view of IO exit as recently increasing. We also show that alternative arguments are not correct: IO exit is not widely occurring because of a backlash against globalization, nationalism/populism, IO authority, or legal rules. Moreover, exit is not inconsequential. We end with a roadmap for each chapter.