This is a complete edition, with prolegomena, translation, and commentary of the first, "philosophical" part of Philodemus' De Pietate, preserved in papyri. Introducing a new method for reconstructing the fragmented papyrus rolls recovered from Herculaneum, this is the first edition based on the papyri themselves (where they still exist), rather than on faulty reproductions, and the first edition to bring together fragments hitherto thought to be fromdifferent rolls. It will also be the first translation of the work into any language. An innovative format presents on facing pages the technical details of the papyrus, and a conventional, continuous text with interpretive notes. The work itself comprises a polemical treatise on the gods, mythography, andreligion, presenting a defence of Epicurus's view of religion as an outgrowth of cultural history, and a philosophical rationale for participation in traditional cult practices in order to further social cohesion.