Now revised and containing three new chapters, this book provides a clear and accessible introduction to epistemology, or the theory of knowledge. It discusses some of the main theories of justification, including foundationalism, coherentism, reliabilism, and virtue epistemology. Other topics include the Gettier problem, internalism and externalism, skepticism, the problem of epistemic circularity, a priori knowledge, naturalized epistemology, and the epistemic significance of testimony and disagreement. Intended primarily for students taking their first classes in epistemology, this lucid and well-written text will provide an excellent introduction to anyone interested in knowing more about this important area of philosophy.