A thorough examination of the acta of the bishops of Bangor in north Wales opens a revealing window into the medieval Welsh Church, and sheds light on the bishops' dealings with popes, archbishops, and religious houses, as well as with the kings of England and princes of Wales. JOINT WINNER: 2025 Francis Jones Prize in Welsh History (Jesus College, Oxford) This volume provides a first edition of the acta (charters, indulgences, letters, petitions, professions of obedience etc) of the bishops of Bangor in north Wales for the period 1092-1306. A period which witnessed momentous change not only for the princes of Wales but also for the Welsh Church. There are 102 acta in total, 24 of which survive as originals, 6 retaining their original seals. Latin transcriptions of the acta are provided in extenso with English summaries. Textual and historical notes follow the transcriptions, with an explanation of the date ascribed to each document. The volume begins with an introduction to the medieval diocese of Bangor, its geographical extent, structure and the personnel responsible for its administration. There is also an examination of the native Welsh clas, which existed before a chapter was introduced. After brief biographies of the ten bishops who held the see during the period covered by the volume, there is an analysis of the diplomatic of the acta, including sealing arrangements. The volume concludes with the bishops' itineraries.