How did Irish emigrants and their millions of descendants retain their Irishness and develop a distinctive Irish diasporic identity? They did it, Colin Barr argues, through the spread of Hiberno-Roman Catholicism across the English-speaking world between the 1820s and 1914. Drawing from research in over one hundred archives across five continents, Barr demonstrates how Irish clergy mastered ecclesiastical politics and consciously usurped non-Irish clergy's control of local dioceses in the United States and parts of the British Empire, a project enhanced from the 1840s onward by mass emigration after the Great Famine. Synodical councils were held in order to impose uniformity in practice and doctrine; clergy were imported from Irish seminaries and colleges sympathetic to Hiberno-Romanism; and dioceses with growing immigrant populations were carved into smaller ones to which Hiberno-Romanist bishops were appointed.

By far the most important Irish Catholic figure was Ireland's first cardinal, Paul Cullen, the rector of the Irish College in Rome, who later became archbishop of Dublin (1852–1878). Through a combination of informal networks that included members of his extended family, Cullen used his friendships in the papacy's “colonial office,” the Propaganda Fide, to advance a version of Catholicism that emphasized loyalty to Roman doctrine and a distaste for political revolution. His views amplified Daniel O'Connell's earlier advocacy of political pluralism and parliamentary government, and O'Connell was used as an icon by the Irish clergy so that support for constitutional Irish nationalism fused with adherence to Romanist beliefs to produce a distinctive Irish diasporic identity that allowed emigrants to express “Irish,” “Catholic,” and, say, “American” or “Australian” sentiments simultaneously. As Barr describes it, from Boston to Brisbane, this Hiberno-Roman identity “emphasized loyalty to both the papacy and to Ireland, encouraged Irish symbolism and Roman devotions, and insisted on communal cohesion and social separation, especially in education and matrimony” (18).

Barr's account of Dublin-born Francis Patrick Kenrick's career is an important contribution to the history of the American Catholic Church. Kenrick received his education in Rome and was appointed coadjutor bishop of Philadelphia in 1830. The decrees he wrote for the Philadelphia synod in 1832 influenced later plenary councils across the global Hiberno-Catholic Church. Appointed archbishop of Baltimore in 1851, his ascendancy—and that of the Irish in the United States—led to “ever-deepening links with Rome” (71). Over the following decades, the growing influence of Paul Cullen, Kenrick's close friend and correspondent, helped spread Hiberno-Roman Catholicism across much of the British Empire. In Newfoundland, where Irish Catholics represented the majority of the population, Hiberno-Roman Catholicism was imposed by the appointment of the Cullenite Thomas Power as bishop of St. John's in 1870. Two years later, Hiberno-Roman Catholicism was brought to New Zealand with the appointment of Patrick Moran as bishop of Wellington. Cullen's influence was arguably greatest in Australia. By the late 1860s, six of Australia's eleven bishops were “products of Cullen's Irish College” (347). The ascendancy of Cullenite Hiberno-Romanists was confirmed in 1884 when Pope Leo XIII personally chose Cullen's nephew, Patrick Francis Moran, to be the next archbishop of Sydney. By the time of his death in 1911, Moran had overseen the rapid development of a Catholic educational infrastructure that was not only Romanist but saturated in “Irish imagery” (399). For students of Australian Catholicism, this book represents the growing trend to emphasize Rome's influence and, through its emphasis on the role of the Irish hierarchy, complements Christopher Dowd's study of the Benedictines in his Rome in Australia: The Papacy and Conflict in the Australian Catholic Missions, 1834–1884 (Brill, 2008).

To his credit, Barr acknowledges places where Hiberno-Roman Catholicism was not so influential. He considers the Irish experience in India a “near-total failure” (149). Additionally, while Romanist doctrines and practices in South Africa were reinforced by Irish symbolism—especially the ubiquitous names of parishes after St. Patrick—that country's racial complexities meant that “Irishness” was largely subsumed within a broader “white” identity. Meanwhile, Irish Catholic bishops in the Maritimes and Upper Canada were generally accommodating with respect to secular education. Indeed, William Walsh, who died in 1859, was “the last true Hiberno-Roman” in the Maritime provinces (281). Barr also highlights the contributions of Irish female religious orders who deserve much of the credit for building Catholic educational infrastructures across the English-speaking world. In Australia, Barr writes, female religious leaders “were not merely the passive transmitters of male ideas or initiatives” but “controlled important and often complex organizations with a significant degree of autonomy and did so while navigating environments that were often hostile to female agency” (352).

The breadth of Barr's vision, based on voluminous research in ecclesiastical records, presents an intriguing and persuasive thesis. This opens the doors for future research into the perspectives of such underreported groups as the nuns who built these communities, the general laity, or those Irish Catholics who challenged the bishops’ teachings. The relative role of diasporic nationalism in bolstering the development of Irish ethnic identities in many of these regions also needs further exploration; it is perhaps no accident that the ascendancy of Hiberno-Roman Catholicism came during the decades leading to Irish independence in 1922. Nevertheless, Barr's emphasis on the commonalities of Irish clergy's practices will benefit future studies of the Irish diasporic identity that employ comparative analysis between regions as Kevin Kenny has suggested in “Diaspora and Comparison: The Global Irish as a Case Study” (Journal of American History 90, no. 1 [2003]: 134–162) and Malcolm Campbell has exemplified in Ireland's New Worlds: Immigrants, Politics, and Society in the United States and Australia, 1815–1922 (University of Wisconsin Press, 2008). For now, in revealing the ecclesiastical web that implemented a Hiberno-Romanist project to varying degrees in places as far flung as North America, India, South Africa, and Australasia, Barr has produced a groundbreaking study of global Catholicism that no student of Irish diasporic studies should ignore.