This book is the first academic all-island history of either rugby union or association football, two of the three most popular male sporting pastimes in Ireland, across the seven decades that followed the political partition of that country between 1920 and 1922. It moves beyond the occasionally simplistic explanations of the development of Irish sport that have focused on political and sectarian divisions, and goes deeper into the social, cultural and geographical dynamics of the island of Ireland to explain why certain people have played certain games in certain places. Drawing on historical and archival sources as well as cutting-edge geographical information systems, the book brings to life the spatial trends in each game’s administrative development and geographical distribution, that have not normally been a feature of many previous histories of Irish sport. The book also examines first-and-second-hand accounts of athletes and administrators involved in rugby and football during that period, to explore what it meant to represent a province or country at these crucial moments in Irish history and compares the Irish experience of both sports with experiences in other comparable countries. Shining important new light on the interactions between Irish rugby and football and the political, social, economic and cultural trends of Ireland in the twentieth century, this book is fascinating reading for anybody with an interest in the history of sport, Ireland or the UK.