The Apostle Paul's reference to the "tongues of angels" (1 Cor 13.1) has always aroused curiosity, but it has rarely been the object of a history-of-traditions investigation. Few readers of Paul's words are aware of the numerous references and allusions to angelic languages in Jewish and Christian texts. John C. Poirier presents the first full-length study of the concept of angelic languages, and the most exhaustive attempt to assemble the evidence for that concept in ancient Jewish and early Christian texts. He discusses possible references to angelic languages in the New Testament, pseudepigraphic writings (both Jewish and Christian), the Dead Sea scrolls, rabbinic texts, patristic references, magical writings, and epigraphy. The discussion is divided between those witnesses that understand angels to speak Hebrew, and those that understand angels to speak an esoteric heavenly language.