The human cost of the Gulag, the Soviet labour camp system in which millions of people were imprisoned between 1920 and 1956, was staggering. Aleksandr Solzhenitsyn and others after him have written movingly about the Gulag, yet never has there been a thorough historical study of this unique and tragic episode in Soviet history. This groundbreaking book presents the first comprehensive, historically accurate account of the camp system. Russian historian Oleg Khlevniuk has mined the contents of extensive archives, including long-suppressed state and Communist Party documents, to uncover the secrets of the Gulag and how it became a central component of Soviet ideology and social policy. Khlevniuk argues persuasively that the Stalinist penal camps created in the 1930s were essentially different from previous camps. He shows that political motivations and paranoia about potential enemies contributed no more to the expansion of the Gulag than the economic incentive of slave labour did. And he offers powerful evidence that the Great Terror was planned centrally and targeted against particular categories of the population. Khlevniuk makes a signal contribution to Soviet history with this exceptionally informed and balanced view of the Gulag.