This collection of papers (including three completely new ones) by one of the foremost philosophers in epistemology transcends two of the most widely misunderstood positions in philosophy - foundationalism and coherentism. Audi proposes a distinctively moderate, internalist foundationalism that incorporates some of the virtues of both coherentism and reliabilism. He develops important distinctions between positive and negative epistemic dependence, substantively and conceptually naturalistic theories, dispositional beliefs and dispositions to believe, episodically and structurally inferential beliefs, first and second order internalism, and rebutting as opposed to refuting scepticism. These contrasts are applied not only to rational belief, but to rational action and the rationality of desires and intentions. The overall position is a pluralist, moderately rationalistic, internalist theory of justification and a partly externalist conception of knowledge. However, by virtue of offering a theory of rationality as well as an account of knowledge and justified belief, it will interest philosophers of ethics, science, and the social sciences and teachers and students of epistemology.