Since the mid-twentieth century, most people in Europe and North America have taken for granted the stability of their liberal democratic institutions. In the postwar decades, some democracies did collapse, but they tended to be weak states in poor countries outside the advanced Western world, such as Argentina, Brazil, Ghana, Peru, and Thailand. Today, as Levitsky and Ziblatt argue in this important study, democracies are dying in slower and more subtle ways—and Western democracies, including the United States, are not immune. The risk comes not from power-hungry generals or revolutionary parties but from elected officials who come to office—often riding a nationalist, populist, anti-elite, anticorruption wave—and proceed to take small steps toward authoritarianism. The threat is so dangerous precisely because each step is often legal. Delivering a powerful wake-up call, Levitsky and Ziblatt see signs of erosion in “the soft guardrails” of democracy in the United States. Decades of extreme polarization have taken their toll on the respect for constitutional checks and balances and on traditional American political norms, such as mutual toleration, acceptance of the legitimacy of rivals, and self-restraint in the use of institutional prerogatives.