The Irish Republican Socialist Party was founded at a meeting on 8 December 1974 in the Spa Hotel in Lucan, near Dublin, by former members of Official Sinn Féin, headed by Seamus Costello. According to the IRSP, 80 people were in attendance. A paramilitary wing, the Irish National Liberation Army (INLA), was founded the same day, although its existence was intended to be kept hidden until such a time that the INLA could operate effectively. Costello was elected as the party's first chairperson and the Army's first chief of staff. Together, the IRSP and the INLA were referred to as the Irish Republican Socialist Movement (IRSM).