For scholars of social stratification one of the key questions regarding educational expansion is whether it diminishes or magnifies existing inequalities in educational attainment. The effect of expansion on educational inequality in tertiary education is of particular importance, as tertiary education has become increasingly relevant for labour market prospects and life course opportunities. Our article studies the access to tertiary education of students with different social origins in light of educational expansion in Germany. First, we examine inequalities in access to four vertical alternatives of postsecondary education by means of multinomial regression with national data from four school-leaver surveys from 1983, 1990, 1994, and 1999. Second, for those students who enrol at a tertiary institution, effects of social origin on horizontal choices of fields of study are analysed. Results show that unequal opportunities to access postsecondary and tertiary institutions remain constant at a high level. Likewise, social background effects have not changed over time for the choice of field of study. Thus, students from different social backgrounds did not change their educational strategies irrespective of the ongoing expansion of secondary and tertiary education.