Tradition takes knowledge to be true, justified belief. Accordingly, any theory of knowledge needs a supplementary theory of belief. It should say what belief is, and especially what features of a belief determine whether the belief is true and justified. Epistemology does not have its own account of belief, but draws on interested branches of philosophy. I present their views and the implications for epistemology. The first section provides general orientation. The next three sections explore belief as viewed by philosophy of language, logic, and philosophy of mind. The section following these considers whether epistemology gains by introducing an attitude of acceptance to supplement or replace ordinary belief. The final section draws conclusions for epistemology.