The Social Democratic and Labour Party (SDLP; Irish: Páirtí Sóisialta agus Daonlathach an Lucht Oibre) is a social democratic and Irish nationalist political party in Northern Ireland. The SDLP currently has eight members in the Northern Ireland Assembly (MLAs) and two members of Parliament (MPs) in the House of Commons of the United Kingdom.
The SDLP party platform advocates Irish reunification and, pending the unity of all the people of Ireland and while the northern jurisdiction remains part of the United Kingdom, further devolution of powers. It is a sister party of the UK Labour Party, which maintains an electoral pact with the SDLP not to stand candidates in Northern Ireland but to support SDLP candidates instead.