This paper is a contribution to the discussion of ethnic residential segregation. Its main objective is to clarify a group of concepts and test how these can be implemented. To this end, two main approaches will be discussed: the first approach will concentrate on the social concept of ethnic segregation and its contribution to the establishment of the social framework of the city and its internal dynamics. The meaning and possibilities of creating different socio-spatial entities – ethnic neighbourhoods, ethnic enclaves and ghettos – will also be discussed. The second approach will be orientated towards the possibilities of implementing the concept of ethnic residential segregation, while discussing methods and limitations of measuring segregation and mechanisms to identify different socio-spatial entities. Both research lines will be used to analyse residential ethnic-segregation in the Lisbon Metropolitan Area (LMA) in 2001. Technical issues related to group categorization of immigrants in the LMA and the construction of geographical units for analysis will be discussed. In addition, evaluation and identification of existing diverse socio-spatial entities in terms of ethnic composition and concentration will be presented. The idea that ghettos are inexistent within the LMA will receive particular attention.

keywords: socio-spatial segregation; segregation measures; immigrants; ghetto; Lisbon Metropolitan Area.