This volume represents papers given at two symposia held at Rennes in 2004–5, together with further contributions. The aim is to take a fresh look at the territories of dioceses in western Europe in the earlier Middle Ages, going beyond the traditional assumption that most late antique dioceses survived into the Middle Ages relatively unchanged to investigate whether there was a concept of diocesan territory between the fifth and the eleventh centuries and if so what it was. Discussion of terminology and concepts is provided by Michel Lauwers in the opening paper. Although the title promises ‘the medieval west’ the volume is essentially about France, especially south of the Loire; outside France, there are only two papers on Italy (by Laurent Feller and Jean-Pierre Delumeau, both concentrating on a diocesan border dispute between Arezzo and Siena), one each on Spain (Patrick Henriet) and Germany (Steffen Patzold, on Magdeburg), and, somewhat exotically, one on Syria in the crusading period (Pierre-Vincent Claverie). Many of the papers are case studies, often focusing on particular disputes between neighbouring sees; in addition two papers look more generally at particular aspects of developing ecclesiastical administration in the twelfth and thirteenth centuries – rural deans (Daniel Pichot) and the extent to which cathedral cartularies reflect the internal organisation of dioceses (Florian Mazel). The French case studies include a valuable account of how Visigoths, Arabs and Franks brought about major changes in the diocesan map of southern Gaul between the Rhône and the Pyrenees between the fifth and ninth centuries (Laurent Schneider), detailed case studies of territorial disputes in Provence, imperial Burgundy, Gascony and Normandy (Yann Codou; Laurent Ripart; Florian Mazel), an account of developments in early Brittany (Bernard Merdrignac and Louisa Plouchart) and a study of the province of Rheims by Charles Mériaux that explores the means by which bishops sought to strengthen their authority in the earlier Middle Ages, in particular through the takeover of monasteries and the development of patronal saints' cults. Each article concludes with a useful dossier of edited and translated sources and maps. Although each author presents an individual view, a firm editorial voice is none the less audible throughout the volume, arguing that in the earlier Middle Ages bishops did not think territorially but in personal and seigneurial terms when trying to assert spiritual authority, and that it was only from the Gregorian period that a new interest arose in defining ecclesiastical authority according to precise geographical boundaries. There is much to be said for this model, but it works better for France than for some other parts of Europe, and the studies of Feller and Patzold, explaining how Ottonian diplomata outlined diocesan boundaries, show this strikingly. In a similar vein might be noted the subdivision of Wessex dioceses along shire boundaries in about 909, and, in the earlier eleventh century, the detailed delimitation of diocesan boundaries between Hereford and Worcester and between Canterbury and Rochester, in the former case required because shire boundaries were different, in the latter because both sees lay in the same shire. Fuzzier edges to dioceses, characteristic of France in the earlier Middle Ages, sometimes resulted from belts of unpopulated forest, sometimes from seigneurial decisions to switch spiritual control of a given area from one bishop to another.