This volume offers an in-depth exploration of the cultural connections between and across Britain, Ireland, and Iceland during the high and late Middle Ages. Drawing together new research from international scholars working in Celtic Studies, Norse, and English, the contributions gathered together here establish the coherence of the medieval Insular world as an area for literary analysis and engage with a range of contemporary approaches to examine the ways, and the degrees to which, Insular literatures and cultures connect both with each other, and with the wider European mainstream. The articles in this collection discuss the Insular histories of some of the most widely read literary works and authors of the Middle Ages, including Geoffrey of Monmouth and William Langland. They trace the legends of Troy and of Charlemagne as they travelled across linguistic and geographical borders, give fresh attention to the multilingual manuscript collections of great households and families, and explore the political implications of language choice in a linguistically plural society. In doing so, they shed light on a complex network of literary and cultural connections and establish the Insular world not as a periphery, but as a centre.