The Cyrenaic school was a fourth-century BC philosophical movement, related both to the Socratic tradition and to Greek Scepticism. In ethics, Cyrenaic hedonism can be seen as one of many attempts made by the associates of Socrates and their followers to endorse his ethical outlook and to explore the implications of his method. In epistemology, there are close philosophical links between the Cyrenaics and the Sceptics, both Pyrrhonists and Academics. There are further links with modern philosophy as well, for the Cyrenaics introduced a form of subjectivism which in some ways preannounces Cartesian views, endorsed by Malebranche and Hume and developed by Kant. This book reconstructs Cyrenaic epistemology, explains how it depends on Cyrenaic hedonism, locates it in the context of ancient debates, and discusses its connections with modern and contemporary epistemological positions.