:For the Lamb of God song Omerta see Omerta (song).

Omertà is a popular attitude, common in areas of southern Italy, such as Sicily, Calabria, and Campania, where criminal organizations like the Mafia, 'Ndrangheta, and Camorra are strong. A common definition is the "code of silence".

Omertà implies “the categorical prohibition of cooperation with state authorities or reliance on its services, even when one has been victim of a crime.” Even if somebody is convicted for a crime he has not committed, he is supposed to serve the sentence without giving the police any information about the real criminal. Within Mafia culture, breaking the oath of omertà is punishable by death.

A common misconception is that the Mafia created or instituted omertà. In fact, the code was adopted by Sicilians long before the emergence of Cosa Nostra (some observers date it in the 16th century as a way of opposing Spanish rule. ) As noted by Harvard anthropologist, Michael Herzfeld, it is also deeply rooted in rural Crete, Greece.