The Socialist Labour Party was a political party in the Republic of Ireland formed under the leadership of Matt Merrigan (Dublin Secretary of the ATGWU) and Noel Browne (TD) in 1977. Another key figure was the radical journalist Brian Trench, now head of the Communications Department at Dublin City University along with the former Clann na Poblachta Roscommon TD Jack McQuillan. The founders came from the Liaison Committee of the Labour Left, which in 1975/76 had tried to build the "Left Alternative", a coalition of progressive organisations and individuals, aimed at addressing what they saw as the cultural and economic impoverishment of Irish society by the establishment parties of Fianna Fáil, and Fine Gael. It had some success in the early 80's with Noel Browne being elected TD in 1981 for Dublin North Central.
The SLP regarded itself as highly progressive. It allowed for the right of factions to organise within the Party. The most notable were the Socialist Workers Tendency, organised around members of the Socialist Workers' Movement which left in 1980, the Workers Alliance for Action organised around members of the Irish Workers Group which left in 1979 and the Republican Socialist Tendency, organised around members of People's Democracy, which also left in 1979.
Following a continuing decline in membership, the SLP was dissolved in 1982.