The Parti social démocratique du Québec (PSD; transl. Social Democratic Party of Quebec) was the Quebec wing of the Co-operative Commonwealth Federation. It was founded in 1939 as the Fédération du Commonwealth Coopératif and was led by Romuald-Joseph Lamoureux in the 1944 general election, by Thérèse Casgrain from 1951 to 1957 and by Michel Chartrand from 1957 to 1960. The name Parti social démocratique was adopted in 1955.

The party was refounded in 1963 as the New Democratic Party of Quebec (Nouveau Parti démocratique du Québec). However, the party soon split over the issue of Quebec self-determination. In November 1963, Quebec nationalists left the PSD to form the Parti socialiste du Québec; the latter was led by former PSD leader Michel Chartrand.

The NDPQ renamed itself the Parti de la Democratie Socialiste (Party of Socialist Democracy) following a 1991 split with the federal NDP over the question of Quebec independence.^[1]

• A candidate ran as "CCF candidate" in the 1936 Quebec general election, although the Quebec section of the party had not been founded yet.

• David Côté, MLA 1944-1948, Rouyn-Noranda

• Politics of Quebec
• List of Quebec general elections
• List of Quebec premiers
• List of Quebec leaders of the Opposition
• National Assembly of Quebec
• Timeline of Quebec history
• Political parties in Quebec