In the changing South Africa of the nineties language planning becomes a top priority on the agenda of constitutional reform. It appears however, that some misplaced enthusiasm is generated by language planners regarding the relatively well defined language regions on a national level. It should be kept in mind that approximately two-thirds of the South African population presently resides in high density urban areas. Contrary to the relatively clear-cut regionalization implied by the rural language patterns, a different form of regional demarcation and language planning is necessary in large metropolitan areas where the population concentrations are the result of a multilingual migration process. Cape Town is a suitable experimental ground to focus the methodological and conceptual shift from a national to an urban resolution level in language mapping. The aim of this paper is to address the following issues: The generalconceptual niche of cities in geolinguistics; the spatial identification ofpresent language distribution in Cape Town; the time-space pattern oflanguage change in Cape Town; the socialprofile of language speakers in Cape Town; and the consequences of the findings forlanguage planning in Cape Town and South Africa. Although Cape Town is linguistically probably one of the least diverse cities in South Africa, three language groups (Africaans, English and Xhosa) are clearly apparent within the limited surface area of the urban space. Their respective distribution patterns are relatively segregated within specific neighbourhoods of the city.