In Colombia as in other Latin American countries, the last decade has brought recognition of ethnic and cultural diversity in the official discourse and in the Constitution. This change is the result, among other factors, of a mobilization by civil society and political and scientific circles over the condition of minorities and the segregation and discrimination processes affecting them. The south-west region and its metropolis Cali, as major seats of the African Colombian and, to a lesser extent, the indigenous population, are at the heart of the issue. Building on a survey conducted in 1998 in Cali, this article raises the problem of measuring and analysing racial segmentation and its links to spatial and social mobility. In the context of a society with a high level of race mixture, what is advocated here is the use of phenotypic categories to capture the complex relations between social and ethnic inequality, and to suggest a preliminary diagnosis of segregation and discrimination in Cali, building on the residential distribution and socio-economic conditions for insertion in the city, but also using the respondents’ perception. The survey also reveals the strong heterogeneity of this population, due largely to its diversified geographic origins and the highly varied historical and economic circumstances of its migration. Lastly, through logistic regressions on the answers to ethnic and phenotypic questions, the article explores the determinants of the African Colombian identity assertion movement that has recently emerged in the country, and suggests a new approach to the question of the black population’s place in the Colombian mixed-race society.