Among the most common criticisms of "popular constitutionalism" has been that its advocates have failed adequately to specify its underlying theory. There are, in fact, countless institutional arrangements by which popular control can be made meaningful. This paper articulates the version developed by James Madison in essays he wrote as Publius and after. It seeks to restore to modern understanding the fundamental popular and democratic character of Madison's theory of deliberative democracy, reinterpreting in particular Federalist 10 and Federalists 49=51. Contrary to conventional wisdom, Madison was wholly committed to majority rule. Rather than seeking to frustrate popular majorities, Madison saw federalism, separation of powers, and extensive size as devices that would generate the kind of public debate needed to inform citizens and secure the sovereignty of a responsible public opinion. A doctrine like judicial supremacy would have been (and was) anathema to this system. A role for courts did ultimately emerge, but it was a minor one in which judicial actions - no less than the actions of executives and legislators - were meant to be subject to popular control.