Aristotle famously said that humans are rational animals and he distinguished two forms or kinds of human rationality. Practical rationality aims to answer questions about how to live and about what sort of person one should be. It deals with human action and the will. Theoretical rationality aims to answer questions about the nature of our world and of our place in it. It deals with human knowledge and the understanding. Philosophical work on rationality aims to understand the similarities, differences, and relations between these forms of reasoning.  Traditionally, philosophers have placed the concept of belief at the heart of accounts of theoretical rationality but have seen it as of only secondary interest to accounts of practical rationality. Instead, they have placed the concepts of desire and intention at the heart of accounts of practical reason. There is no doubt that belief is central to theoretical reasoning since theoretical reasoning aims at knowledge and belief is essential to knowledge. Indeed, on the traditional philosophical conception, to know something just is (or at least requires having) a true and justified belief. But philosophers have usually viewed belief as of only secondary interest to an account of practical rationality. Belief is relevant to action, in this view, only because we ought to consult our beliefs before we decide how to act to satisfy our desires and to form and carry out our intentions and plans. Beliefs, on this view, are a bit like maps we rely on in deciding where to go and how to get there. The papers in this volume are all concerned in one way or another with this traditional philosophical conception of the relations between belief on the one hand and intention and action on the other.