Sinn Féin traces its origins to the Irish nationalist politics associated with Arthur Griffith in the early twentieth century. The precise organisational genealogy is more complicated than a single founding moment: the Sinn Féin name was in use from around 1905, while nationalist groups were brought together under a more formal organisation in the years immediately afterwards.
Revolution and partition
The party’s fortunes were transformed after the 1916 Easter Rising. In the 1918 general election Sinn Féin won a large majority of Irish seats, and its elected representatives assembled in Dublin as the First Dáil rather than taking their seats at Westminster. The subsequent War of Independence and negotiations with Britain produced the 1921 Anglo-Irish Treaty.
The Treaty divided the republican movement. Supporters and opponents went on to form competing political traditions in the Irish Free State, while the Sinn Féin organisation continued as a smaller abstentionist republican party.
The modern party and the Troubles
The modern Sinn Féin organisation was reshaped amid the republican split of 1969-70 and the Troubles. It became closely associated with the Provisional republican movement. The party’s electoral strategy expanded during the 1980s, while its MPs maintained a policy of abstention from the House of Commons.
The peace process
From the late 1980s and 1990s, contacts involving Sinn Féin leader Gerry Adams, SDLP leader John Hume and the British and Irish governments formed part of the broader process that eventually led to IRA ceasefires and the 1998 Good Friday Agreement. Sinn Féin supported the Agreement and entered the new Northern Ireland institutions.
In subsequent decades the party became one of the two largest parties in Northern Ireland and a major party in the Republic of Ireland. Its constitutional objective remains Irish unity, pursued through political and electoral means. Its Westminster MPs continue not to take their seats because the party rejects the required oath of allegiance to the monarch.
Sinn Féin official website · historical material from RTÉ and parliamentary records.