Mafia, name given to a number of organized groups of Sicilian brigands in the 19th and 20th cent. Unlike the Camorra in Naples, the Mafia had no hierarchic organization; each group operated on its own. The Mafia originated in feudal times, when lords hired brigands to guard their estates in exchange for protection from the royal authority. The underlying assumption of the Mafia was that legal authorities were useless and that justice must be obtained directly, as in the vendetta. Italian attempts to curtail the Mafia have suffered from political corruption and the assassination of judges.

Through emigration the organization spread to the United States (where it was sometimes called the Black Hand). It is involved in many illegal operations—trade in narcotics, gambling, prostitution, labor union racketeering—and certain legal enterprises, such as trucking and construction, in the United States. In Nov., 1957, more than 60 of its alleged leaders were surprised at a secret meeting at Apalachin, N.Y. About one third of them were convicted of obstructing justice, but the convictions were reversed on appeal. In recent years, the Mafia has been linked with money-laundering and police corruption and has also been hampered by defections. While slowing its activities in extortion and racketeering in the 1980s and 90s, the contemporary Mafia has expanded into such white-collar criminal enterprises as fraud in health insurance, sales of prepaid telephone cards, and illegal stock market deals.

See also organized crime.