Brian Mac Cuarta suggests that the Catholic resurgence in early seventeenth-century Ireland has been neglected. In part, want of evidence is to blame. However, by employing richly varied sources, including correspondence in the Vatican Archives, he sets out to remedy the neglect. To make the project manageable, he favours a regional approach – in his case concentrating on the province of Ulster. As becomes clear, his chosen area, while showing some common features (the tenacity within it of Gaelic traditions), also exhibits contrasts. The period opens with widespread destruction of buildings and of organisation thanks to warfare. Thereafter, Protestantism and new settlement, ostensibly by Protestants, are promoted by the government. The results varied and were not always what had been intended. The traditionalist earl of Tyrone, before his flight in 1607, emerges as a supporter of reform along the lines decreed at the Council of Trent. In contrast, some newcomers – the Hamiltons (later earls of Abercorn) and the Macdonnells, earls of Antrim – patronised Catholicism. The plantation by London companies of what would become Londonderry, because of their need of tenants and the indulgence of the Protestant bishop, afforded refuge to Catholics throughout the 1630s. The prevalent poverty of Ulster Catholics meant that fewer from the province than from Munster and Leinster were sent to be trained in continental Europe. Since Mac Cuarta's definition of the north includes parts of Leinster settled by earlier English immigrants – notably Meath, Westmeath and Louth – he can make telling comparisons with the situation in the southerly districts of his region. He brings out strikingly the importance of peers and landed gentry as patrons of the Tridentine priests. He emphasises the pivotal importance of the port of Drogheda where a complex religious culture developed. He shows, too, the successes of and tensions between new preaching orders, chiefly the Jesuits and Capuchins, and the older ones headed by the Franciscans. Unedifying rivalries erupted. Parochial clergy resented the encroachments of the mendicants; lay-people were coerced into almsgiving. Divorce was encouraged because of the payments given to complaisant priests. The dues demanded by the clergy of both confessions intensified and perpetuated anticlericalism. Tithes triggered a rebellion against the intruded Protestant incumbents in 1614. Given his detailed description of the numerous conflicts, Mac Cuarta's insistence on a ‘pan-Catholic alliance’, which developed in opposition to Protestant assertiveness, is not altogether persuasive. Even allowing for the fragmentary nature of the evidence, it might have been possible to show how Catholicism thrived in the benevolent atmosphere after 1632. Also, the recorded episodes of violence in and after 1641 could cast retrospective light on attitudes towards the competing clergy. As it is, the systematic assembling and discussion of often unfamiliar evidence enables Mac Cuarta to offer a much fuller account of the reception of Tridentine Catholicism in the north of Ireland than hitherto has been available. His thought-provoking account contributes valuably to the continuing debates as to when and why the Protestant reformation failed and Ireland became a predominantly Catholic island.