Stephen F. Cohen presents a critical analysis of the prevailing view that Mikhail Gorbachev’s six-year attempt to transform the Soviet Union along democratic and market lines proved that the system was, as most specialists had always believed, unreformable. Ideological, conceptual, and historical assumptions underlying the nonreformability thesis are reexamined and found wanting, as are the ways in which generalizations about “the system” and “reform” are usually formulated. Cohen then asks how each of the system’s basic components-the official ideology, the Communist Party and its dictatorship, the nationwide network of soviets, the monopolistic state economy, and the union of republics-actually responded to Gorbachev’s policies. Citing developments from 1985 to 1991, Cohen argues that all of those components, and thus the system itself, turned out to be remarkably reformable. If so, he concludes, most explanations of the end of the Soviet Union, which rely in one way or another on the unreformability thesis, are also open to serious question.