Private prisons have become fundamental to prison reform in the United States, Australia, and the United Kingdom. Privatization is viewed as a departure from the previous norm of public sector imprisonment. Any description and evaluation of privatization must be measured against those known characteristics, strengths, and deficiencies of the public sector. This essay discussed these issues, focusing on the following questions: (1) is imprisonment a State function that must only be managed directly by the State; (2) is there a danger that the commercial opportunities that imprisonment may provide lead to the creation of a powerful penal lobby whose views could distort criminal justice policy; (3) will imprisonment cost actually be reduced and will the private prison regime standards deteriorate; (4) how effective is a private contract in securing enhanced performance in an area dealing exclusively with human lives; (5) what regulatory systems and accountability mechanisms are required and what are the assurances that they will be effective; and (6) will privatization offer a stimulus for improvement in prison regimes as a whole? It is acknowledged that private prisons will remain. Private prisons have been seen to provide solid advantages and benefits while also posing some political and humanitarian risks. However, the risks grow as the motive of cost reduction becomes more predominant. Private prisons must meet State and community standards making the regulatory systems and accountability mechanisms that govern their operations imperative. Private prisons can stimulate improvement of the total prison system if they are properly regulated and held accountable to the public.