Privatization as an economic policy is extremely popular worldwide. Studying it helps political scientists assess the value of liberal, Marxist and neo-institutionalist theories of state growth, because privatization is assumed to be the opposite of the enlargement of state function. These theories all fail to fully explain privatization. Liberalism does not explain its global popularity. Marxism cannot account for it in formerly communist countries, such as Russia. Neo-institutionalism regards the state itself as an independent variable and so cannot explain changes in state size.