Readers should not be put off by the term ‘Celtic world’ in the title of this book – the stated purpose of the volume is to emphasise how certain saints cults transcended linguistic, cultural and political boundaries throughout the medieval period. Indeed, a good proportion of the articles will be of direct interest to English readers, in particular James Fraser's insights into the growing cult of St Andrew among the Picts and Anglo-Saxons, and Fiona Edmond's analysis of the growth of Patrician personal names amongst the Northumbrian nobility. Steve Boardman's chapter on the cult of St George persuasively argues that this saint's popularity in late medieval Scotland and England is attributable to his universal appeal among the European martial classes, while Sally Crumplin demonstrates that veneration for St Cuthbert in Scotland transcended political divisions in the Borders during the twelfth century. Accompanying this is Joanna Huntington's analysis of Aelred of Rievaulx's Life of King David i as an exemplar of good kingship for Henry ii. Eila Williamson's examination of the cult of the Three Kings of Cologne demonstrates the importance of connections with the English and Danish royal houses for enhancing its popularity in Scotland. Beyond this, readers will find plenty of meat for the transmission of cults within and across the Brittonic and Gaelic-speaking regions. Thomas Clancy credibly argues that Patrick's cult in Strathclyde was alive before the destruction of Dumbarton Rock in ad 870, and suggests that the cult of Palladius in north-east Scotland points to ecclesiastical networks between Ireland and Pictland. John Reuben Davies provides a thought-provoking analysis of the development of Kentigern's cult in Wales and Strathclyde in the context of diocesan reform in these regions during the twelfth century, while Karen Jankulak's revision of the phenomenon of ‘recurrent adjacency’ (i.e. the tendency of Brittonic saints' dedications to occur in close geographical proximity in different regions) effectively deconstructs the picture propagated by E. G. Brown and G. H. Doble. Jonathan Wooding's detailed study uncovers how St Brendan's cult developed with shifting political and religious allegiances in Ireland and how his popularity in the British Isles was chiefly the result of the literary cult. The book benefits from a fair amount of cross-referencing between the various chapters, which provides further internal coherence to the work, demonstrating how certain themes are applicable across the discipline. Some readers may be surprised to find that there is no chapter on Columba, though given the amount of recent scholarly attention that this saint has received ahead of others, this is perhaps no bad thing. Most of the chapters concentrate largely upon ecclesiastical dedications, toponymic evidence and hagiography, with less attention to saints' relics and reliquaries. A couple of the chapters would also have benefitted from an extra map or two (especially Jonathan Wooding's article on the medieval and early modern cult of St Brendan) to guide the reader through the discussion. None the less, this is an excellent, thoroughly researched and well-produced volume and a welcome addition to the body of literature in the field.