The purpose of this research is to integrate in a simple way international macroeconomics and trade theory in order to analyze the relationship between optimum currency areas and the localization of production. The first chapter provides a formal model which captures most of the real and monetary arguments discussed within the optimum currency area literature in the last thirty-five years.

The most original and innovative contribution is given in the second chapter, which investigates the relationship between exchange rate regimes and the location choices of firms. The main result is that countries tend to be more specialized under flexible rates than under fixed rates.

The third chapter develops a new model of location choices which combines a Ricardian comparative advantage with product differentiation, monopolistic competition, increasing returns to scale, and trade cost. Countries specialization depends positively on productivity differential and returns to scale, and negatively on trade costs.