New Democratic party (NDP), Canadian political party, founded in 1961 when the Cooperative Commonwealth Federation (CCF) reorganized itself and entered into close ties with Canadian labor unions, especially the Canadian Labor Congress (CLC). The CCF, formed in 1932, began as a largely W Canadian federation of farm, labor, and socialist groups with a democratic socialist program of increased welfare measures, moderate nationalization, and government economic planning. It had some success, especially in western provinces, and was the majority party in Saskatchewan (1944–64). Since then the NDP has put less emphasis on specific socialist proposals in an attempt to broaden its appeal. Its gradual movement away from strongly socialist policies ultimately led in 2014 to the removal of references to socialism from its constitution.

Under the leadership of Thomas C. Douglas (1961–71), David Lewis (1971–75), Edward Broadbent (1977–89), and Audrey McLaughlin (1989–95, the first woman to head a Canadian national political party), the party improved its showing in E Canada, but its main strength remained in the west, where, since the 1970s, it has formed provincial governments at various times in Manitoba, Saskatchewan, British Columbia, and (in the 21st cent.) Alberta. The NDP also has held power in Ontario (1990–95), Nova Scotia (2006–13) and Yukon (1985–92, 1996–2000). Alexa McDonough became party leader in 1995; Jack Layton succeeded her in 2003. The elections of 1993, 1997, and 2000 saw the NDP's representation in Ottawa severely reduced, but those of 2004, 2006, and 2008 reversed that trend, and in 2011 the NDP won 103 seats—the second largest bloc—to become the official opposition. Seriously ill, Layton took a health leave from the leadership in mid-2011; after his death, Thomas Mulcair was elected (2012) to succeed him.