AbstractUsing panel data of 192 countries from 1970 through 1999, and 195 currency crisis episodes, this study examines the effect of membership in a currency union on the probability of experiencing a currency crisis. Both parametric and non‐parametric estimates suggest that membership in a currency union reduces the likelihood of a currency crash. This finding is robust to various definitions of currency crises and exchange rates, across time, and across regions. The results are further confirmed by case studies of some countries that joined or left a currency union. We interpret these findings to suggest that the formation of currency unions should not be ruled out in the debate on stability and the new financial architecture. Copyright © 2008 John Wiley & Sons, Ltd.