The 20th Legislative Assembly of Quebec was the provincial legislature in Quebec, Canada that existed from August 17, 1936, to October 25, 1939. The Union Nationale led by Maurice Duplessis was the governing party for the first time ever.

• After the 1936 elections

This was the list of members of the Legislative Assembly of Quebec that were elected in the 1936 election:

Other MLAs were elected during the term in by-elections

• Joseph-Emile Perron, Union Nationale, Beauce, March 17, 1937 ^[1]
• Philippe Adam, Union Nationale, Bagot, February 16, 1938 ^[2]
• Antonio Talbot, Union Nationale, Chicoutimi, May 25, 1938 ^[3]
• Louis Fitch, Union Nationale, Montréal-Saint-Louis, November 2, 1938 ^[4]
• Henri Gérin, Union Nationale, Stanstead, November 2, 1938 ^[5]

• Prime Minister and Executive Council President: Maurice Duplessis
• Agriculture: Bona Dussault
• Mines, Hunting and Fishing: Onésime Gagnon (1936)
  • Mines and Fishing: Onésime Gagnon (1936–1939)
• Colonization: Henri Lemaître Auger
• Labour: William Tremblay
• Public Works: John Samuel Bourque
• Lands and Forests: Oscar Drouin (1936–1937), Maurice Duplessis (1937–1938), John Samuel Bourque (1938–1939)
• Health: Albiny Paquette (1936–1939)
• Roads: François-Joseph Leduc (1936–1938), Maurice Duplessis (1938), Anatole Carignan (1938–1939)
• Municipal Affairs, Industry and Commerce: Joseph Bilodeau
• Attorney General: Maurice Duplessis
• Provincial Secretary: Albiny Paquette
• Treasurer: Martin Beattie Fisher
• Members without portfolios: Antonio Élie, Thomas Chapais (1936–1939), Gilbert Layton, Thomas Joseph Coonan

The electoral map was reformed in 1939 just prior to the elections later that year.^[6]

• Châteauguay and Laprairie were merged to form Châteauguay-Laprairie while Napierville which was merged with Laprairie was merged with Saint-Jean to form Saint-Jean-Napierville.
• Kamouraska and Rivière-du-Loup were merged to form Kamouraska-Rivière-du-Loup
• Westmount was split into two new ridings: Montréal-Notre-Dame-de-Grâce and Montréal-Outremont.
• Montréal-Jeanne-Mance was formed from parts of Maisonneuve, Montréal-Mercier and Montréal-Dorion.
• Montréal-Saint-Georges was renamed Westmount-Saint-Georges.
• Richelieu and Verchères was merged to form Richelieu-Vercheres
• Vaudreuil and Soulanges were merged to form Vaudreuil-Soulanges.