Data was collected from archival records, site visits, and interviews with police, criminals, and journalists. Contrary to expectations, the reality of organized crime was found to be quite removed from the myth of the Mafia. While the city shows a clear history of dominance by powerful organized crime groups, from about 1917 to 1960 organized crime was largely the territory of an Irish and a Jewish cabal. In the 1960's, the Cosa Nostra family of Angelo Bruno played a larger role, but still held only a small share of organized criminal activity. Involvement in gambling, fencing, labor racketeering, loan-sharking, prostitution, and drug trafficking was shared by the Mafia, Jews, Greeks, Irish, motorcycle gangs, and hundreds of smaller crime groups. No ethnic group dominated or dominates crime in Philadelphia. Ethnicity has played only an ancillary role, one dictated more by urban demography and criminal exigencies. Organized crime has survived and flourished because it is an integral part of the political system and the economy. The police, local government, and political establishment tolerate vice for a share of the profits; it is this association that constitutes the only city-wide organization of crime in Philadelphia. Crime and vice are run by a clique of police, businessmen, and bureaucrats: it is not genology which organizes crime but power and money. Eleven figures and a 153-item bibliography, are included.