This article examines the changing role of Irish-America in the Northern Ireland peace process and contends that it played a pivotal role in the Provisional IRA's announcement in July 2005 that it was ending its campaign of violence. It is argued here that the IRA decision to end its campaign was influenced considerably by three separate but interrelated factors: (1) the internationalization of Northern Ireland by successive US governments beyond the limits of domestic UK politics; (2) the evolution of the Irish-American political lobby in the 1990s, from outcome-driven objectives to process-driven and attainable goals; and (3) the current leadership of the Irish republican movement has orientated itself around the changing social fabric of Irish-America, which is smaller and less cohesive than in the past. More broadly, the article demonstrates the way in which the dynamics of internal conflict can be altered by external actors via the use of `soft power' strategies, in a manner that can assist the development of a peace process.