The membership was set by the 1940 federal election on 26 March 1940, and it changed only somewhat due to resignations and by-elections until it was dissolved prior to the 1945 election.

It was controlled by a Liberal Party majority under Prime Minister William Lyon Mackenzie King and the 16th Canadian Ministry.

The Official Opposition was the so-called "National Government" party (the name which the Conservatives ran under in the 1940 election), led in the House by Richard Hanson and Gordon Graydon consecutively as the three successive national leaders of the party, Robert Manion, Arthur Meighen and John Bracken did not have seats in the House of Commons.

With the selection of Bracken as national leader in December 1942, the party became known as the Progressive Conservatives.

There were six sessions of the 19th Parliament: Following is a full list of members of the nineteenth Parliament listed first by province, then by electoral district.