Many contemporary Anglo-American philosophers describe themselves as naturalists. But what do they mean by that term? Popular naturalist slogans like, "there is no first philosophy" or "philosophy is continuous with the natural sciences" are far from illuminating. "Understanding Naturalism" provides a clear and readable survey of the main strands in recent naturalist thought. The origin and development of naturalist ideas in epistemology, metaphysics and semantics is explained through the works of Quine, Goldman, Kuhn, Chalmers, Papineau, Millikan and others. The most common objections to the naturalist project - that it involves a change of subject and fails to engage with "real" philosophical problems, that it is self-refuting, and that naturalism cannot deal with normative notions like truth, justification and meaning - are all discussed. "Understanding Naturalism" distinguishes two strands of naturalist thinking - the constructive and the deflationary - and explains how this distinction can invigorate naturalism and the future of philosophical research.