This article focuses on analysing the effect of educational differentiation policies of OECD educational systems on socioeconomically disadvantaged students, based on data from PISA 2009. The analysis is conducted on the basis of a definition of two subgroups of disadvantaged students: those that achieve high scores, and those obtaining scores that are significantly below the average for their country. Educational systems are classified in four models following the classification proposed by N. Mons. Results show that the more integrated the educational system, the greater the number of disadvantaged high achievers, and the lower the number of disadvantaged low achievers.