Unlike most other developed countries, Italy hosts a few, large-scale, century-old criminal organizations that not only engage in profit-making criminal activities but also exercise quasi-political functions in their areas of settlement, heavily influencing the local economic and political life. These criminal organizations—in short “mafias”—are frequently seen as the ultimate epitome of organized crime. The first section of the essay briefly reconstructs the history of the concept “mafia,” singling out the main meanings that have over the decades been attached to it. The second presents the main criminal organizations currently regarded as mafias in Italy. The bulk of the essay argues that four characteristics distinguish mafia organizations in Italy and mafia-type organizations elsewhere: (1) the organizations’ longevity, (2) their organizational and cultural complexity, (3) their claim to exercise a political dominion over their areas of settlement—a claim that has over the decades been at least partially recognized by the local population and parts of the official government, and (4) their resulting ability to control legitimate markets. The essay argues that the Sicilian Cosa Nostra and the Calabrian ’Ndrangheta meet all four characteristics, whereas several groups of the camorra, which are based in Naples and its surroundings, meet the latter two. The essay concludes by briefly summarizing government and societal anti-mafia action from the early 1990s onward and considering how mafia groups have reacted to it.