The Progressive Era of the early twentieth century witnessed sustained condemnation of individualism and individual rights. The intellectual currents of the Progressive era called into question the individualist values of classical liberalism, and paved the way for the political triumph of the New Deal. Most historians agree that John Locke had an enormous influence on the Founding generation. Locke's classical liberalism, with its focus on natural law and the rights of individuals, was reflected in the Declaration of Independence as well as the constitution-drafting experience at both the state and federal level in the years following the American Revolution. The rapid changes in American society at the end of the nineteenth century stimulated the Progressive movement. Drawing upon Darwinian theory, Richard T. Ely rejected the Lockean concept of natural rights and denied the existence of natural law. This chapter considers the impact of progressivism upon constitutional jurisprudence.