provincial Canadian political party founded in 1968 by journalist René Lévesque (Lévesque, René) and other French Canadian separatists in the largely French-speaking province of Quebec.

In 1968 Lévesque merged his Mouvement Souveraineté-Association (Sovereignty-Association Movement)—which advocated Quebec sovereignty in a new kind of looser association of Canadian provinces—with other separatist groups to form the Parti Québécois. Unsuccessful in the Quebec provincial elections of 1970 and 1973, the party in 1976 won 71 of 110 seats in the provincial National Assembly, and Lévesque was elected premier. The following year the Assembly decreed French (French language) the only official language of government and business in Quebec, and in 1980 Lévesque organized a referendum seeking approval for the provincial government to negotiate a new status and relationship with the rest of Canada. The referendum failed, however, with only two-fifths of Quebecers supporting sovereignty-association talks; those voting against the proposal included a small majority of French speakers.

The party maintained its dominance in Quebec's provincial assembly at the beginning of the 1980s, but membership declined thereafter as separatist fervour waned. In 1985 the independence plank was removed from the party's platform, and, following a series of defections and by-election defeats that year, Lévesque resigned; the Parti Québécois was swept from power in December. By 1987 the party was again controlled by militant separatists, and, when there was a resurgence in support for Quebec separatism in the 1990s, the party's hopes revived. It had informal ties with the Bloc Québécois, a Quebec separatist party that captured most of the province's seats in the House of Commons in the 1993 federal elections and served as the country's official opposition party from 1993 to 1997.

The Parti Québécois won 77 out of 125 seats in the 1994 provincial election and formed a government under its leader, Jacques Parizeau. In 1995 the party held another referendum seeking popular approval to negotiate Quebec's secession from Canada; again the proposal was rejected, though this time it lost by only 1 percent of the vote. Lucien Bouchard, the leader of the federal Bloc Québécois and Canada's former ambassador to France, became head of the party in 1996 and led it to victory in the 1998 provincial elections. Bouchard resigned as premier of Quebec in 2001 and was replaced as leader of the party and as premier of Quebec by Bernard Landry. In the provincial elections of 2003 the Parti Québécois was reduced to 45 seats and was ousted from power by the Liberals. In 2007 the party suffered its worst result since 1973, winning only 36 seats and falling into third place.