Sinn Fein, (Gaelic for “Ourselves Alone”), an Irish political party. It played a leading role in the revolt against British rule in Ireland that resulted in the establishment of the Irish Free State. Sinn Fein was founded in 1905 by Arthur Griffith. In 1917 Eamon de Valera, a leader in the independence movement, became president of Sinn Fein, which in 1919 declared Ireland independent and began fighting the British.

After Britain recognized the Irish Free State in 1922, Sinn Fein split into factions. Extremists committed to immediate revolution eventually gained control of the party. By the late 1960's Sinn Fein had become the political arm of the Irish Republican Army (IRA), joining its attempt to end British rule in Northern Ireland. In 1994, after the Provisional IRA announced an end to hostilities, representatives from Sinn Fein and Britain began negotiations. In 1997 Sinn Fein won two seats in the British Parliament. On April 10, 1998, Sinn Fein, along with seven other Northern Ireland political parties, signed an agreement creating the Northern Ireland Assembly, designed to replace direct rule from London. In the first elections to the Assembly, Sinn Fein won 18 of its 108 seats.