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| 1957, June 17 |
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| Following the Conservatives' victory in the June 10 parliamentary elections, John Diefenbaker formed a new cabinet, the first Conservative government in 22 years. | 1 |
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| 1958, Jan. 16 |
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| Lester B. Pearson succeeded St. Laurent as leader of the opposition Liberal Party. | 2 |
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| March 31 |
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| Prime Minister Diefenbaker and the Conservative Party won the greatest election victory in Canada's history, securing 202 seats of the 265 in the federal House of Commons. | 3 |
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| April |
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| The Gordon Commission report was released. It expressed concern over the growing level of U.S. investments in the Canadian economy since 1945. | 4 |
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| July 10 |
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| U.S. president Dwight D. Eisenhower and Prime Minister Diefenbaker agreed in Ottawa to establish the Canada–United States Committee on Joint Defense. | 5 |
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