This is a revised edition of a book originally published in 1982. It incorporates both new material which has become available during the last three decades and a substantial amount of further thinking on the part of the author. It is not a narrative history; it portrays and analyses a medieval society and community, showing what kind of place Anglesey was in the middle ages and illustrating the effect on the island and its people both of events in contemporary Wales and of developments common to most of medieval Europe.