This volume offers a view of the current state of play in epistemology, in the form of twelve new essays by some of the philosophers who have most influenced the course of debates in recent years. Topics include epistemic justification, solipsism, skepticism, and modal, moral, naturalistic, and probabilistic epistemology. Such approaches as reliabilism, evidentialism, infinitism, and virtue epistemology are here developed further by the philosophers who pioneered them.