This article examines Irish nationalist attitudes towards electoral reform between 1885 and 1918. It argues that before 1917 mainstream Irish nationalist opinion attached little importance to the franchise, being instead more concerned about the consequences for home rule if the number of Irish parliamentary seats was reduced through redistribution. However, the introduction of wartime legislation to reform the franchise and registration system repoliticized electoral reform in nationalist Ireland. While the Irish parliamentary party vociferously protested at the coalition government's belated attempt to redistribute Irish constituencies, its critics (a coalition of heterodox nationalists, socialists, and suffragettes) accused it of deliberately conspiring to exclude Ireland from the ‘fourth’ reform bill because the young men and women it would enfranchise intended to vote for Sinn Fein. This article argues that the concerns of the Irish party regarding redistribution were genuine and legitimate, while the conspiracy theory was essentially a propaganda device. None the less, the theory gained widespread attention because its underlying assumption about the voting behaviour of the new electorate was shared not only by its exponents, but by sections of the press, the British administration in Ireland, and the Irish party itself. Indeed, so convinced was the party that the cleavage in Ireland was as much generational as ideological that ultimately the franchise was a factor in its defeat at the 1918 general election.