O’Leary’s authoritative treatment of the history of Northern Ireland and its current prospects is genuinely unique. Beginning with an in-depth account of the scale of the recent conflict, he sets out to explain why Northern Ireland recently had the highest incidence of political violence in twentieth-century western Europe. Volume 1 demonstrates the salience of the colonial past in accounting for current collective mentalities, institutions, and rivalrous animosities, culminating in a distinct comparative account of the partition of the island in 1920. The major moments in the development of Irish republicanism and Ulster unionism are freshly treated by this Irish-born political scientist who has spent thirty-five years mastering the relevant historiography. Volume 2 shows how Ulster Unionists improvised a distinctive control system, driven by their fear of abandonment by the metropolitan power in Great Britain, their anxieties about Irish nationalist irredentism, and their inherited settler colonial culture. British political institutions were exploited to organize a sustained political monopoly on power and to disorganize the cultural Catholic minority. At the same juncture, the Irish Free State’s punctuated movement from restricted dominion-level autonomy to sovereign republican independence led to the full-scale political decolonization of the South. Irish state-building had a price, however: it further estranged Ulster Unionists, and Northern nationalists felt abandoned. Volume 3 unpacks the consequences and takes the reader to the present, explaining Northern Ireland’s distinctive consociational settlement, accomplished in 1998, and its subsequently turbulent and currently imperiled implementation. An assessment of the confederation of European Union and the prospects for an Irish confederation close the book, which vividly engages with feasible futures that may unfold from the UK’s exit from the EU.