Organized crime or criminal organizations are groups or operations run by criminals, most commonly for the purpose of generating a monetary profit. The Organized Crime Control Act (U.S., 1970) defines organized crime as "The unlawful activities of ... a highly organized, disciplined association...".

Some criminal organizations, such as terrorist organizations, are politically motivated. Gangs sometimes become "disciplined" enough to be considered "organized". An organized gang or criminal set can also be referred to as a mob. The act of engaging in criminal activity as a structured group is referred to in the United States as racketeering. In the U.S., organized crime is often prosecuted federally under the Racketeer Influenced and Corrupt Organizations Act (RICO), Statute (18 U.S.C. Part I Chapter 96 §§ 1961-1968).

Organized crime, however defined, is characterized by a few basic qualities including durability over time, diversified interests, hierarchical structure, capital accumulation, reinvestment, access to political protection and the use of violence to protect interests.