John Adams was unique among the Founding Fathers in that he actually read and took seriously Machiavelli's ideas. In his Defence of the Constitutions of the United States, Adams quoted extensively from Machiavelli and he openly acknowledged an intellectual debt to the Florentine statesman. Adams praised Machiavelli for having been “the first” to have “revived the ancient politics” and he insisted that the “world” was much indebted to Machiavelli for “the revival of reason in matters of government.” What could Adams have meant by these extraordinary statements? The following article examines the Machiavellian ideas and principles Adams incorporated into his political thought as well as those that he rejected. Drawing upon evidence found in an unpublished fragment, Part one argues that the political epistemology that Adams employed in the Defence can be traced to Machiavelli's new modes and orders. Part two presents Adams's critique of Machiavelli's constitutionalism.