General readers should be forewarned that this book is written from a rational-choice perspective, which is currently the rage in academic political science. While the author provides plain English explanations of his findings at the beginning and end, readers will have to confront a considerable amount of math as the author seeks to model different kinds of authoritarian rule in terms of the interests of the regime's different actors. The best chapters concern the decline of the Soviet Union, where a rational-choice perspective is actually quite helpful in understanding why it was that the Soviet Communist Party could not prevent competition and dissent within its own ranks from ultimately weakening its rule. As in most rational choice accounts, the models are weakest in accounting for moral factors and historically contingent events. The subject of regime legitimacy -- how just the elites supporting the regime feel it to be, which is different from the author's "loyalty" variable -- cannot simply be reduced to the question of how rents are distributed or how much repression is used. Nor can models explain the embarrassing fact that, had Yegor Ligachev instead of Mikhail Gorbachev succeeded Konstantin Chernenko, the Soviet Union would likely still be with us today.