This edition collects all the surviving evidence for the fifth-century BCE Athenian sophist Antiphon and presents it together with a translation and a full commentary, which assesses its reliability and significance. Although Antiphon is not as familiar a figure as sophists such as Protagoras and Gorgias, substantial fragments have survived from his major works, On Truth and On Concord, including extensive remains preserved on papyrus. In addition, information about his doctrines is preserved by ancient writers ranging in time from Aristotle to Simplicius and beyond. The introduction provides a brief sketch of Antiphon, his works, and his place in the fifth-century BCE sophistic movement, including his important contribution to the contemporary debate over the relation of law (nomos) and nature (physis). It also deals with the controversial question of the identity of Antiphon the sophist in relation to Antiphon of Rhamnus and other men of the same name.