This article discusses the return on investment of localization, which is defined here as the process of adapting software, products, documentation, or Web sites to local market needs. According to continuous research at Common Sense Advisory, localization efforts cost a small fraction of the international revenue they generate. Nonetheless, most firms in the United States underfund their localization budgets. In this article, the author recounts focused research into the localization practices of 50 U.S. companies. He introduces a step-by-step process for measuring and ensuring the ROI of localization projects, considering a wide range of standard business paybacks and offers formulas for calculating returns. Practitioners can draw on the experiences of others and on these metrics to demonstrate shareholder value to corporate budgeters mindful of post-Enron accounting scrutiny.