This, the first full-scale study of Welsh surnames, is built on research in Welsh, Latin, and English texts, parish registers, local histories, and more. It traces the growth of a Welsh surnaming pattern in Wales and the Border region at the end of the Middle Ages, and it fleshes out that picture through evidence from contemporary sources such as electoral registers, newspapers, and telephone directories. It will be of use to historians, genealogists, geographers, sociologists, and more.