Grandes écoles, specifically French prestigious schools of university level, are often presented as the training ground for the nation's elite. The only way into these schools is to pass the competitive entrance examination, which is a strict selection process supposedly based solely on individual merit. Yet the grandes écoles are regularly accused of encouraging the social reproduction of the elite by accentuating the social inequalities of educational success rates, especially as regards postgraduate studies for which entry conditions are theoretically less strict. An analysis of the social background of students who entered these grandes écoles from the 1940s to the 1980s highlights the patent ongoing cultural and social selection. Sons of executives and teachers still have a much better chance of entering a grande école than children from working class backgrounds in a period marked by widespread secondary school education with many social stratification changes. In terms of the relative chances of entry based on social background, the social enrolment base of the grandes écoles seems to have narrowed in the 1980s following relative democratisation in keeping with the rest of the higher education system. The explanation for these heightened grande école entry inequalities could be found in both their own greater selectiveness to preserve their exclusivity and in the easier entry to postgraduate studies increasingly offering vocational training.