In government, bicameralism (Latin bi, two + camera, chamber) is the practice of having two legislative or parliamentary chambers compromise bills.

Bicameralism is an essential and defining feature of the classical notion of mixed government. Bicameral legislatures tend to require a concurrent majority to pass legislation.

Although the ideas on which bicameralism are based can be traced back to the theories developed in Ancient Sumer and later ancient Greece, ancient India, and Rome, recognizable bicameral institutions first arose in medieval Europe where they were associated with separate representation of different estates of the realm. For example, one house would represent the aristocracy, and the other would represent the commoners.

The Founding Fathers of the United States also favored a bicameral legislature. The idea was to have the Senate be wealthier, and (apparently) wiser. "The Senate was created to be a stabilizing force, elected not by mass electors, but selected by the State legislators. Senators would be more knowledgeable and more deliberate—a sort of republican nobility—and a counter to what Madison saw as the 'fickleness and passion' that could absorb the House.