In the United States and abroad, a populist surge threatens the assumptions and achievements of politicians and policy makers from mainstream parties. In the United States, populist discontents have been fueled by an array of factors, including the Great Recession that resulted from the 2008 financial crisis; the failure of past reforms to stem the tide of illegal immigration over the country’s southern border; the economic consequences of sweeping technological change; and the rise of an education-based meritocracy that has left less-educated citizens in outlying towns and rural areas feeling denigrated and devalued. Today, some parties on both the left and right are calling into question the norms and institutions of liberal democracy itself. Growing insecurity has triggered a demand for strong leaders, and forms of authoritarianism that many believed had been left behind for good a quarter-century ago are threatening to resurface. These developments illuminate the historical case for liberal democracy, as well as the sources of its current weakness.