A minority government is one that emerges from an election with fewer seats in the House of Commons than the combined total of all other parties.
For any government to work, it needs to be able to pass legislation. A minority government can't survive unless it can secure enough support from opposition parties — which comes at a price.
Sometimes the government decides that the price for support is too high. There are some bills (especially budgets and other money bills) that are considered non-confidence votes. If the government loses a non-confidence vote, it will fall. It's then up to the Governor General to either ask the leader of the party with the next most seats to try to form a government or dissolve Parliament and clear the way for another election.
Minority governments are usually short-lived. They last an average of about 18 months. The last Conservative minority government, led by Joe Clark, lasted only nine months.
Here are the minority governments that Canada has had since Confederation:
William Lyon Mackenzie King (Liberal)
1921 election: Liberal (116); Progressive (50); Conservative (63); Labour (3); and Other (3)
Result: Mackenzie King leaned heavily on support from the Progressives to complete his term. High on his agenda was reducing tariffs and freight rates – an issue close to the hearts of Prairie farmers (who comprised much of the membership of the Progressive party).
1925 election: Conservative (114); Liberal (102); Progressive (24); Labour (2); and Other (3)
Result: Despite winning the most seats in the election, Arthur Meighen's Conservatives did not form the government. Both they and King's Liberals sought the support of the small Progressive party, and King lured over enough MPs that he was able to run a government for eight months. When he lost a confidence motion over the Customs Scandal, he went to Gov. Gen. Lord Byng asking him to dissolve Parliament so that the country could go to an election. Byng refused, and Byng called on Meighen's Conservatives to form the new government, which they did.
Within days, the new government lost a vote of confidence and Byng was forced to dissolve Parliament and allow an election after all. King campaigned on the constitutional issue of the Governor General refusing to accept his earlier request for dissolution, and won the election. This has become known as the King-Byng affair.
1926 election: Liberal (117); Conservative (91); UFA (11); Progressive (11); Liberal Progressive (9); and Other (6)
Result: With support in the House from the Progressives, the Liberals worked on paying down the war debt and introduced the old age pension.
John Diefenbaker (Progressive Conservative)
1957 election: PC (113); Liberal (103); CCF (25); Social Credit (19); Independent (2) and Other (3)
Result: Having won a slim election victory, Diefenbaker and his ministers campaigned to increase their popularity before calling a general election in 1958. The tactic worked brilliantly and the party won 208 of 265 seats.
1962 election: PC (116); Liberal (99); Social Credit (30); NDP (18); Other (2)
Result: Once again Diefenbaker and his party were in a minority situation. The government had become embroiled in the debate over whether or not Canada should have nuclear weapons as part of a continental defence shield (he was against the idea). The controversy led to a vote of non-confidence in February 1963, forcing Diefenbaker to call a general election. He and the PC party were defeated by a narrow margin by the Liberals. Diefenbaker's second mandate lasted less than one year.
Lester Pearson (Liberal)
1963 election: Liberal (128); PC (95); Social Credit (24); NDP (17) and Other (1)
Result: Only four seats short of a majority, Pearson called an election in 1965. Once again he and his party came up short – this time with 131 seats.
1965 election: Liberal (131); PC (98); NDP (21); Ralliement des Créditistes (9); Social Credit (4) and Other (2)
Result: The Liberals relied on the support of the New Democratic and Social Credit parties to govern effectively. Pearson was the first prime minister in Canadian history to never head a majority government.
Pierre Trudeau (Liberal)
1972 election: Liberal (109); PC (107); NDP (31); Social Credit (15) and Other (2)
Result: Elected by an extremely small plurality (41 per cent of seats versus the PCs' 40.5 per cent), Trudeau called an election within two years and won it by a more comfortable margin (53.4 per cent of seats).
Joe Clark (Progressive Conservative)
1979 election: PC (136); Liberal (114); NDP (26) and Social Credit (6)
Result: Clark's government tried to introduce fiscal policy that proved unpopular. Only seven months into office his attempt to pass legislation was defeated in the House, forcing an election call. Trudeau and the Liberals won back a slim majority.
Joe Clark was the second prime minister in Canadian history to never have a majority government.
Paul Martin (Liberal)
2004 election: Liberal (135); Conservative (99); Bloc Québécois (54); NDP (19); and non-affiliated (1)
Result: The Liberals under Paul Martin survived a near-death experience to win Canada's first minority government in 25 years on June 28, 2004.
The political knives were out within months and less than a year after the election, it looked as though the government would not last. In the end, it came in near the average for a minority government: 17 months.
Stephen Harper (Conservative)
2006 election: Conservative (124), Liberal (103), Bloc Québécois (51), NDP (29), Independent (1) (Just before the government was sworn in, David Emerson left the Liberals to join the Conservative cabinet, boosting their seat total to 125 and reducing the Liberals to 102)
Result: The Conservative Party of Canada – the product of the merger of the Canadian Alliance and the Progressive Conservative parties – made major gains in Quebec and Ontario and took enough seats to form a government, ending 12 years of Liberal rule. The government lasted 937 days, Canada's longest uninterrupted minority, before Harper triggered an election in September 2008.
2008 election: Conservative (143), Liberal (77), Bloc Québécois (49), NDP (37), Independent (2)
Result: Harper returned to power with a stronger mandate increased by electoral gains in Ontario.