Abstract Since the start of the Northern Ireland conflict in 1969, the Irish Republican Army (IRA) has been committed to a military campaign to achieve a British withdrawal from the province. The adoption of a parallel electoral strategy in the 1980s and 1990s represents a fundamental change of tactics. This article outlines the background to this change, and analyses the electoral success of the IRA’s political wing, Sinn Fein. Using survey data collected over four decades, the results show that Sinn Fein’s electoral support has come mainly from previous non-voters and new voters, at a time when the Catholic proportion of younger voters has been increasing. The net effect has been to increase the overall nationalist and republican vote, with no decrease in the Social Democratic Labour Party vote. The personal influence of Gerry Adams, the Sinn Fein president, together with public support for the IRA’s military campaign, helps to account for Sinn Fein’s mobilization of these voters. The strategy of pursuing parallel military and electoral campaigns has paid major political dividends for Irish republicans.