Hugo Lundhaug and Lance Jenott examine the provenance of the Nag Hammadi Codices and defend the view that they were produced and read by Christian monks of Upper Egypt in the fourth and fifth centuries. Eschewing the modern classification of these texts as Gnostic, the authors analyze the codices in the context of the diverse monastic culture of late antique Egypt, with special attention to monasticism in the Thebaid and controversies over extra-canonical books and the theological legacy of Origen. The question of ownership is examined by means of a detailed study of the Nag Hammadi Codices' scribal notes and colophons, the cartonnage papyri from the leather covers, and scribal habits and codicology, seen in comparison with contemporary Coptic and Greek biblical manuscripts, as well as a range of sources for Upper Egyptian monasticism.