Contrary to warnings about the dangers of populism, Donald F. Critchlow argues that grassroots activism is essential to party renewal within a democratic system. Grassroots activism, presenting a cacophony of voices calling for reform of various sorts without programmatic coherence, is often derided as populist and distrusted by both political parties and voters. But according to Donald T. Critchlow, grassroots movements are actually responsible for political party transformation, both Democratic and Republic, into instruments of reform that reflect the interests, concerns, and anxieties of the electorate. Contrary to popular discourse warning about the dangers of populism, Critchlow argues that grassroots activism is essential to party renewal within a democratic system. In Defense of Populism examines movements that influenced Republican, Democratic, and third-party politics—from the Progressives and their influence on Teddy Roosevelt, to New Dealers and FDR, to the civil rights, feminist, and environmental movements and their impact on the Democratic Party, to the Reagan Revolution and the Tea Party. In each case, Critchlow narrates representative biographies of activists, party leaders, and presidents to show how movements become viable calls for reform that get translated into policy positions. Social tensions and political polarization continue to be prevalent today. Increased social disorder and populist outcry are expected whenever political elites and distant bureaucratic government are challenged. In Defense of Populism shows how, as a result of grassroots activism and political-party reform, policy advances are made, a sense of national confidence is restored, and the belief that American democracy works in the midst of crisis is affirmed.