At a meeting in the Lucan Spa Hotel near Dublin, on 10 December 1974, the Irish Republican Socialist Party was formed by republicans, socialists, and trade unionists with Costello as the Chairperson.
Under ett möte i Lucan Spa Hotell nära Dublin den 10 december 1974 skapades Irish Republican Socialist Party, IRSP, av republikaner, socialister och handelsfackmän med Costello som ordförande.