Liberal party, Canadian political party. Prior to confederation in 1867, reform parties advocating greater local participation in provincial governments, free trade, and increased separation of church and state existed in Canada West, Canada East, and the Maritime Provinces. After 1867 although the provincial reform parties dominated local politics in several provinces, they had problems establishing a viable national party. The only Liberal prime minister in the first three decades after Confederation was Alexander Mackenzie.

The lack of a strong base in Quebec hampered national Liberal party efforts. However, opposition in Quebec to the execution of French-Canadian rebel Louis Riel, and the success of Wilfrid Laurier in moderating the traditional anticlericalism of the Quebec Liberal party, paved the way to national success. As prime minister at the turn of the century, Laurier provided the model for future Liberal party successes by forging a broad coalition based on an English-French alliance that appealed to middle-class interests.

For most of the 20th cent., the Liberal party dominated Canadian politics. William Lyon Mackenzie King's long tenure as Liberal prime minister during most of the 1920s, 30s, and 40s successfully encompassed the diverse and sometimes contradictory interests of a wide English and French constituency. Under King's Liberal successor, Louis St. Laurent, the party lost most of its base in the western provinces. Under Lester Pearson, the party slowly rebuilt its electoral base, although for much of his tenure as prime minister in the 1960s he headed a minority government.

Bilingualism, constitutional questions, and the status of Quebec dominated the tenure of Liberal Prime Minister Pierre Trudeau, who was succeeded briefly as prime minister by John Turner in 1984. Turner remained leader of the Liberal party until 1990, when he was briefly replaced by Herb Grey; later that year Jean Chrétien became Liberal party leader. In 1993 dissatisfaction with the economy returned the Liberals to power; they remained in power against a divided opposition after the 1997 and 2000 elections. Paul Martin became party leader and prime minister in 2003 and, despite being hurt by scandals, the Liberals remained in office as a minority government after the 2004 elections.

In the 2006 elections the Liberals were again hurt by scandal. The Conservatives won a plurality of the seats, and Martin resigned as Liberal leader; Stéphane Dion succeeded him in the post. The Liberals suffered further losses in the 2008 elections, and Michael Ignatieff became party leader when Dion resigned later in 2008. The party suffered its worst defeat in 2011, placing third behind the Conservative and New Democratic parties, and Ignatieff stepped down. Bob Rae, the former premier of Ontario (as a New Democrat), was interim party leader until Justin Trudeau, son of Pierre Trudeau, was elected in 2013.