This article analyzes the effects of family background and the socioeconomic context of the school and state on students' achievements in mathematics and language at the end of secondary education in Argentina. The study examined data of 150,000 students in 3,300 high schools. Multilevel linear modeling with three levels (student, school and state) was used to analyze the family background and context effects on achievement. The results are discussed in term of the theory of distributive justice (Rawls) and the concept of equality of educational opportunity (Coleman). It was found that the educational achievement is affected by the strong socioeconomic segmentation of the institutional educational system and that the cultural capital indicators are the most important predictors.