This article contends that liberalism in America underwent a fundamental transformation during the Progressive Era. This transformation took place, partly, through the Progressives' reinterpretation of the doctrine of property rights that had served as a foundation for founding-era liberalism. Progressives rejected the eighteenth-century, natural-rights principles which had privileged individual rights to life, liberty, and property as the fundamental aims of any just government, and argued instead that America at the turn of the twentieth century was beset by a tyranny of (...) the minority which was employing property rights to inhibit genuine freedom for the bulk of the population. This article examines the character of founding-era liberalism and points to the connection between the political theory of the Declaration of Independence and John Locke's Second Treatise of Government. It then provides an account of the Progressive critique of this original version of American liberalism. The Progressive critique is shown to take two forms: a rejection of property rights in principle, followed by a rejection of them in practice. (shrink)