Agallamh na senorach 'The colloquy of the ancients' is the core of the cycle of stories centered on the legendary character Finn mac Cumaill, his fian 'warrior band,' his son Oisin, and his grandson Oscar. It is concerned with the encounters between St. Patrick and the last surviving Fenian warriors, most notably Cailte and Oisin. The Agallamh survives in numerous different versions dating from the late medieval/early modern Irish period to folklore versions collected in the modern era. The contributions in this volume range across all the extant versions. Initially delivered as conference papers to honor Prof. Sean O Coileain, these studies comprise the first ever book-length treatment of the subject.