The Workers' Party (Irish: Páirtí na nOibrithe) is an Irish republican, Marxist–Leninist communist party active in both the Republic of Ireland and Northern Ireland.
The party formerly asserted a claim of direct descent from the original Sinn Féin organisation founded in 1905 by Arthur Griffith. It took its current form in 1970 following a division within Sinn Féin, in which the majority faction followed the leadership in a Marxist direction. It was known as Sinn Féin (Gardiner Place) or Official Sinn Féin, to distinguish it from the minority faction of "Sinn Féin (Kevin Street)" or "Provisional Sinn Féin". It changed its name from Sinn Féin to Sinn Féin The Workers' Party in 1977 and then to the Workers' Party in 1982. In that time, Provisional Sinn Féin came to be known simply as Sinn Féin. Both groups were tied to corresponding paramilitary groups, with Official Sinn Féin tied to the Official Irish Republican Army.