Beginning in the 1980s, countries across southern and Eastern Europe, Latin America, and Asia made transitions to democracy. In recent years, this "third wave" of world democratization has slowed and, in some cases, reversed. This important book presents fascinating empirical findings that explain why some countries have become democracies and others have not, and why some democratic breakthroughs have endured and others have slid backward. Echoing the classic work of the political scientist Adam Przeworski, Teorell argues that modernization primarily helps prevent reversals to authoritarianism rather than promote transitions to democracy. Interestingly, he suggests that this "modernization effect" has to do with the spread of media: a free press seems to undercut antidemocratic coups. Short-term economic gains, meanwhile, can reinforce authoritarian rule, whereas sudden economic crises can trigger pro-democracy movements. Teorell also finds evidence of a "diffusion effect," whereby a successful democratic transition in one state can stimulate efforts elsewhere. The book's rich findings will no doubt stir the scholarly debate and lend support to democracy promoters who wish to strengthen pro-democratic groups and independent media.