How liberal was the American founding? The answer to that question depends entirely on how one defines “liberal” and the history of liberty. Several popular conservative writers share a common, negative assessment of liberalism as relatively new and negative, arguing that it ought to be distinguished from and rejected by American conservatism. This lecture argues the contrary. Properly understood in its historical context, the American founding was liberal. While its particular liberal polity was certainly new, the elements of its liberalism, grounded in English common law, natural law, and Christian history and theology, largely are not. In particular, this lecture surveys the antecedents to American liberalism in the Church Fathers and medieval Christendom.