This article aims to establish, on the basis of a mixed explanatory sequential estimate, how actors of the educational system (teachers and school managers) use academic and social mechanisms to distance strong students from the weak by means of categorizing or distributing them unevenly and differently in the school space. On the theoretical level, while relying on Bourdieu's structuralist constructivism, cultural discontinuity theory and systemic discrimination as a framework for analysis, this study combines three approaches to the sociology of education (functionalist, conflictualist and the approach of rational choices) as epistemological base, to try to understand the dynamics of school segregation and the mechanisms, by which it reflects the social relations of inequality. From a methodological point of view, it begins an empirical research conducted in the Western Department, starting; on the one hand, from a survey conducted by questionnaire with 303 actors (100 teachers, 95 parents, 13 managers of institutions and 95 students), and four group interviews with five teacher groups, four individual interviews with principals. Using quantitative and qualitative methods in an explanatory mixed sequential quote process, quantitative data analysis is followed by qualitative analysis to consolidate and explain the quantitative results.