In January of this year, Jamil Mahuad, then president of Ecuador, startled his compatriots by proposing to eliminate the national currency, the sucre. Instead, Mahuad advanced, the U.S. dollar would replace the sucre for all purposes. Although a popular uprising forced him out of office a week later, the succeeding government has actually implemented his proposal and recently announced that U.S. dollars will have completely replaced the sucre by September 2000. ; The question remains as to whether the Ecuadorian plan will be successful and, more generally, whether other countries will follow Ecuador's lead. But one thing is clear: proposals to replace the domestic currency with the U.S. dollar, or to "dollarize" the economy, have taken center stage in Latin America and other developing regions. To illustrate why dollarization has risen from neglect to such a central role, this article discusses the currently fashionable proposals for dollarization in Latin America and other developing regions. ; The article places special emphasis on identifying and analyzing various arguments for and against dollarization in the light of existing economic theory and evidence. The author compares the relative significance of the costs and benefits. Observing that measurement problems are significant, he concludes that, remarkably, the popular belief that dollarization is a desirable reform has been reached in spite of widespread uncertainty about its economic benefits.