The problem of the "foundations of ethics" is one of the oldest and most venerable in philosophy, discussed in a literature that stretches from the Platonic dialogues to the present. It is also, despite its currency, a remarkably obscure and multifarious problem: it's rarely clear in the literature what "the" problem is, what the solutions are, and indeed, what counts as an instance of either problem or solution. The basic aims of this study are to defend a particular conception of the problem; to offer the sketch of a solution; and to offer an extended critique of one attempted solution, namely, Christine Korsgaard's in The Sources of Normativity. Topics discussed include foundationalism as a general theory of epistemic justification, intuitionism as a moral epistemology, and meta-ethical approaches to the foundations of ethics (notably Kantianism and egoism). Principal figures discussed include Aristotle, Kant, Mill, Moore, Rawls, and Korsgaard.