This analysis of the reform movements in American politics from 1890-1940 reviews: (1) The agrarian uprising that found its expression in the Populist movement of the 1890's; (2) The Progressive movement from about 1900 to 1914; (3) The New Deal of the 1930's. Emphasis is placed upon the ideas of the leading political reformers, their aims and techniques, and the combined effect of all of these things upon American thinking.