This is the fourth in a series of five volumes that were published simultaneously (in what was surely a remarkable feat of editorial coordination) covering the history of British and Irish Catholicism from 1530 to 2021. Volume four, from 1830 to 1930, comprises sixteen chapters ranging from the essential features of Catholicism in the British Isles – bishops, priests, parishes, schools, devotional life, church-state relations – to more specialized topics, such as Catholic music and fiction. It is good to see specific chapters on the hugely significant Irish diaspora and on Catholic overseas missions. This book breaks down the silos that have developed between Catholic history in Ireland, where it has long been a mainstream area of scholarly enquiry, and the rest of the British Isles, where it has been treated as the story of a marginalized community, building its identity in the face of various types of English, Scottish and Welsh Protestantism. The editors acknowledge the extent to which some contributors moved beyond their comfort zones to write about Catholics and Catholicism across the four nations and two islands of Britain and Ireland. That they were willing to do this is essential to the book’s success. Furthermore, it highlights research – particularly in the form of local studies – that is often tucked away in small journals, doctoral theses, or essay collections. The chapters are clear, concise, and helpful, but much of the value of the book lies in the footnotes, which point readers to a rich range of further sources. As most of the standard histories of nineteenth-century British Catholicism are somewhat dated, and some of the Irish histories intersect very broadly with other themes, it is a great benefit to have both a clear synthesis of and an authoritative guide to so much recent research in this one volume.