This dissertation consists of three independent essays addressing several key issues related to the empirical application of optimum currency area. The first essay explores the features of the CFA franc zone by operationalizing Robert Mundell’s (1952) criteria for an optimum currency area. A vector autoregression method is used in modeling national outputs as determined by global, regional and country-specific shocks. It finds that domestic outputs of the CFA franc zone countries are strongly influenced by country-specific shocks. These results suggest that the CFA franc zone countries are structurally different from each other and the monetary union may have been a costly arrangement for the member countries. The second essay focuses on the Eastern Caribbean Currency Union (ECCU). A 2-vairable vector autoregressive model is estimated to investigate the extent of symmetric shocks in the small open economies of the ECCU. The paper finds that domestic outputs of the ECCU countries are strongly influenced by regional shocks. These results indicate that the ECCU countries are structurally similar to each other and exchange arrangements appear to have well served the region and the group of countries is more likely to be an optimum currency area. The third essay explores the possibility of a currency union in East Asia. In this essay, the extent of global and regional integration in East Asia is investigated using the stock price index as a measure of economic performance. A similar VAR model is employed to separate the underlying shocks into global, regional and country-specific shocks. The estimation results show that country-specific shocks play a dominant role in East Asia although their role appears to have declined over time, especially after the 1997 financial crisis. Global and regional shocks are responsible for small but increasing shares of stock price fluctuations in most countries. The results indicate that, despite years of liberalization and regional integration, economies in East Asia remain dissimilar and are subject to asymmetric shocks and it might be costly for East Asian countries to abandon monetary policy independence to form a monetary union and that a more flexible exchange rate regime might be desirable.