Though it has never had a complete monopoly on organized crime in Chicago, the Outfit has long been the most powerful, violent and largest criminal organization in Chicago and the Midwest in general. He shared power with Tony Accardo from 1943 until his death in 1972 Accardo became the sole power in the Outfit upon Ricca's death and was one of the longest-sitting bosses of all time upon his death in 1992. Capone was convicted of income tax evasion in 1931 and the Outfit was next run by Paul Ricca. Since then, the Outfit has been involved in a wide range of criminal activities, including loansharking, illegal gambling, prostitution, extortion, political corruption and murder. The Outfit rose to power in the 1920s under the control of Johnny Torrio and Al Capone, and the period was marked by bloody gang wars for control of the distribution of illegal alcohol during Prohibition. It is part of the larger Italian-American Mafia.

The Chicago Outfit (also known as the Outfit, the Chicago Mafia, the Chicago Mob, the Chicago crime family, the South Side Gang or The Organization) is an Italian-American organized crime syndicate or crime family based in Chicago, Illinois, which originated in the city's South Side in 1910. Various Chicago gangs, historically the North Side Gang and Irish Mob