An inner-urban area characterized by the spatial concentration of disadvantage. The term is often associated with particular ethnic groups—for example black North Americans—and was originally applied to the urbanized Jewish populations of Europe. The classic study is by Louis Wirth, who argued that the ghetto could only be understood as a social psychological as well as an ecological phenomenon, since ‘it [the ghetto] is not so much a physical fact as it is a state of mind’ (The Ghetto, 1928). In this respect, much of Wirth's analysis prefigures his later classical essay on ‘Urbanism as a Way of Life’ (American Journal of Sociology, 1938), and should be read against this broader theoretical background. See also urban sociology; urbanism.