This book deals with the genesis and dynamics of exchange rate crises in fixed or managed exchange rate systems. It provides a comprehensive treatment of the existing theories of exchange rate crises and of financial market runs. It aims to provide a survey of both the theoretical literature on international financial crises and a systematic treatment of the analytical models. It analyzes a series of macroeconomic models and demonstrates their properties and conclusions, including comparative statics and dynamic behaviour. The models cover the range of phenomena exhibited in modern crises experienced in countries with fixed or managed exchange rate systems. Among the topics covered, beyond currency sustainability, are bank runs, the interaction between bank solvency and currency stability, capital flows and borrowing constraints, uncertainty about government policies, asymmetric information and herding behaviour, contagion across markets and countries, financial markets and asset price bubbles, strategic interaction among agents and equilibrium selection, the dynamics of speculative attacks and of financial crashes in international capital markets. The book is intended for econometricians, academics, policymakers and specialists in the field, and postgraduate students in economics.