The study cautiously identifies exchange rate misalignment as an important element in most of the exchange rate crises that plagued the developing world during the last decade. Given that the increasing integration of world capital markets, has escalated the costs of such crises, a broad consensus emerged in recent years, that the overriding objective of exchange rate policy in developing countries, should be to avoid episodes of prolonged, and substantial misalignment, i.e., situations in which the actual real exchange rate differs significantly from its long-run equilibrium value. It was the Bank's involvement in one such misalignment episode, that eventually led to this book. Following an overview on the concepts and measurement of exchange rate misalignment, its impact on the purchasing power parity, and the relationship between the external real exchange rate (RER), and the two-good internal RER for tradables non-tradables, the study presents methodologies - empirical applications - for estimating the RER equilibrium. The study reaches an optimistic conclusion - that enough is known to identify cases of misalignment, and be able to sound clear warning signals. The implication for exchange rate policy is that ignorance about the empirical value of the equilibrium exchange rate, cannot be used to clinch arguments for extreme exchange arrangements, such as clean floats, currency boards, and "dollarization."