The overview concludes that in terms of numbers of personnel and annual expenditures, private policing is the dominant trend in policing in many nations; and this trend is likely to continue and even accelerate. Part of this growth in private security is the emergence and growth of transnational security conglomerates. Also, a diversity of commercial security activities has become part of national and subnational public institutions such as fire departments, ambulance services, car assistance services, custodial services, and even military operations. It is expected that transnational contract security will expand its functions in serving local and national public and private domains across countries. Among the factors that have fueled this trend toward the increasing use of private security are the expansion of site-specific commercial enterprises such as shopping malls, sports stadiums, and leisure facilities of various types. As these facilities draw increasing numbers of people, the need to control and/or prevent antisocial and criminal behavior also increases. Other factors are the fear of crime among the public, increasing crime rates, and weak performance by government-supported policing. Research on private security should include differences and similarities in private security in various countries; structures of accountability for private security; competing principles for public and private security; and the effects of private security on civil liberties, privacy, access to information, human rights, and personal safety. Data are provided on private security trends in various countries and regions of the world. 3 tables, 6 notes, and 75 references