The fourth-century bishop of Cyprus, most well-known for his massive (and, it is often assumed, mendacious) work of heresiology, is not often taken seriously by modern scholarship. One exception is in Epiphanius's preservation of otherwise lost sources: "heretical" writings from the first centuries of Christianity as well as various documents (letters, creeds, council minutes) from his own immediate theological contexts. This communication asks about the contexts, contents, and consequences of Epiphanius's life-long fascination with others' books (beginning, according to Epiphanius, with his youthful encounter with "gnostics" in Egypt). The material and ideological aspects of book collection have received renewed interest in recent classical studies, yet Epiphanius's own seemingly substantial library remains unexamined. What can we know about the bishop's library, both materially and ideologically? In a cultural context where we are apt to see reading practices as narrow indicators of partisan religious membership--through stricter canons or interpretive rules--Epiphanius's library reminds us that ancient Christians often deliberately, ostentatiously, and provocatively read "other" texts precisely in order to police the bounds of Christian identity. Yet the diversity of the heresiologist's library also signals the internally unstable effects of such bibliographic appropriation.