Quebec Act, legislation passed by the British Parliament in 1774 for governing Canada, at that time called the Province of Quebec. The act continued French civil law in the province, admitted Roman Catholics to full citizenship, and permitted the Catholic Church to retain privileges it had when the area belonged to France. The Quebec Act withheld a representative assembly, providing instead for government of the province by an appointed governor and council. It also extended the boundaries of the province to include land between the Appalachian Mountains and the Mississippi River north of the Ohio.

The act was designed largely to win the loyalty of the French in the province, and may have been influential in keeping them from joining in the American Revolution. However, the act infuriated the colonies to the south because it added to Quebec lands that these colonies had previously claimed. They considered the Quebec Act as one of the "Intolerable Acts" adopted by Great Britain in 1774. The Declaration of Independence meant the Quebec Act when it denounced Great Britain "For abolishing the free System of English laws in a neighbouring Province, establishing therein an Arbitrary government, and enlarging its boundaries . . . ."

The Treaty of Paris (1783), ending the American Revolution, gave the disputed territory to the United States. The Quebec Act was further modified in 1791 by the Constitutional Act, which divided the province into Upper and Lower Canada, with each permitted to elect its own assembly.