The purpose of this article is to show that the stratification of the Quebec high school market contributes to the reproduction of social inequalities in higher education. The results obtained from a sample (N = 2,677) of a cohort of students born in 1984 and observed up to the age of 22 show that the influence of social origin operates in large part via mediation of the type of institution attended. Students enrolled in private or public institutions offering enriched programs (in mathematics, science or languages) are significantly more likely to access college and university education than their peers who attended a public institution offering only regular programs. Additional analyses reveal that the probability of attending a private or public institution offering enriched programs is strongly correlated with the social origin of the student. The influence of the education market itself operates through differences in performance and educational aspirations that characterize students in three types of establishments.