The author first examines empirical evidence on the performance of three monetary regimes: the classical gold standard, Bretton Woods, and the current float. As a backdrop, he examines the mixed regime interwar period. Next, he examines why Bretton Woods endured for only 25 years (or less) by linking regime success to the presence of credible commitment mechanisms, that is, to the incentive compatibility features of the regime. He finds that successful fixed-rate regimes, in addition to being based on simple transparent rules, contained features that encouraged a center country to enforce the rules and other countries to comply.