“Social Partnership” was the corporatist socio-economic governance system that functioned in Ireland 1987-2012. It is studied primarly from a political-economic perspective, focusing on problems of classification, e.g. whether it conformed to Keynesian “policy concertation” or “competitive corporatism”, or represented “networked policy making”, “advocacy coalition” or a functionalist co-opting of dissent. Economists question its impact on Ireland’s economic transformation, and comparative analyses find many aspects of it rendering it an “outlier”. Most studies concur that if not quite sui generis, it awaits explanation in domestic political terms. Few have examined its political dynamics or interaction in party-political conflict. These are the aims of this thesis. The absense of such an analysis is partly due to a poverty of sources. This thesis gained unique access to archives of key decision-making partnership bodies, including the NESC, the “Central Review Committee” (in D/Taoiseach), and union and business bodies, and also interviewed 35 key players. The thesis disproves generally accepted theories of partnership as a product of 1980s crisis and “Europeanisation” and a susequent evolution towards dysfunctional “groupthink”. It identifies instead its roots in party/interest group politics, and the political tendency which from the 1950s pursued “corporatism” as a means to overcome structural underdevelopment and drive socio-economic take-off. It identifies the political dynamic of the key 1987 PNR Agreement, and the compromises accounting for the system’s unique features and subsequent evolution. It establishes the political-entrepreneurial nexus of Charles Haughey collaborating with particular business and union leaders, and their agendas to re-organise state and economy. It argues that virtually all aspects of partnership as it maintained to 2012, from economic restructuring and local development to social reform, were initiated in 1987-92, marking that period as the decisive institutional rupture. It also identifies the political factors re-shaping partnership, gradually weakening its economic focus and re-orientating it to welfare state goals. This weakening had removed it from a central role by the time the state again faced crisis in 2008