Information for this monograph was obtained from police officials, representatives of government agencies, politicians, schoolteachers, social workers, Republicans (Catholic advocates), Loyalists (Protestant advocates), and investigative journalists. After providing background information on Republican and Loyalist paramilitary (terrorist) organizations, the monograph reviews their racketeering activities. Although revolutionary ideology and commitments are not completely dead in Northern Ireland, they are secondary to economic expediency. What has emerged in Northern Ireland since the early 1970's is not simply a number of rival criminal organizations which protect their own fiefdoms, but more of a loose-knit Irish 'mafia' that bleeds Protestants and Catholics alike. Loyalist and Republican gangsters not only negotiate over the territory in which each can operate its criminal schemes, but they often cooperate with each other in the administration of the various rackets, Most of the racketeering activities of the paramilitaries are identical to that practiced by conventional North American crime families. When engaged in marginally legitimate businesses, such as pubs and taxi cab operations, they use violence to intimidate and eliminate legitimate competitors. They are also engaged in various forms of building trade rackets. They shy away from prostitution, pornography, and drug trafficking for fear of alienating the populace whose support they need. The future may see the evolution of more sophisticated criminal enterprises, the expansion of the paramilitaries into more legitimate businesses to wield more economic power, and the potential for involvement in drug trafficking. Chapter notes.