Using multilevel models, the authors tested the hypothesis that high schools, through their curricular policies, operate as mechanisms that help members of privileged groups to take better advantage of postsecondary opportunities. The analysis was based on a 7-year follow-up study of 44,666 Israeli students who graduated from 385 high schools in 1991. The main findings were that (a) the curricular experience of students partly mediated between their sociodemographic characteristics and postsecondary enrollment, (b) the curricular arrangements of schools fully mediated the effects of their social composition on their graduates' postsecondary education, and (c) graduates of socially privileged schools made a better use of their matriculation certificates. This afforded privileged students an additional advantage. (Contains 4 tables and 5 notes.)