In the 1980s, several Latin American countries suffered through years of high inflation, as did Israel. Today, high inflations thwart reform and impede recovery in Russia, Ukraine, and most of the other former Soviet republics. This book examines the emergence of such inflation-prone monetary regimes, the financial predicaments besetting governments in high inflations, and the difficulties of devising policy strategies that can be sustained through disinflation to lasting stabilization. It discusses the manner in which these inflations cause the functioning of the market economy to deteriorate. High inflations interfere with information flows between agents and complicate economic calculations; they make the accounting measurement of economic results and the monitoring of principal-agent relationships more difficult; they undermine the basis for intertemporal contractual commitments, and cause many financial markets to disappear entirely. These high inflation phenomena challenge our understanding of monetary economics. Episodes of extreme monetary instability make us see the scope and limitations of current theory in clearer perspective. Theories of money and finance that introduce money only so as to determine the nominal scale of non-monetary general equilibrium will not explain the deterioration of economic performance characteristic of high inflations. The authors conclude this study with an exploration of the theoretical issues raised by the anomalous evidence from the high inflations.