This paper analyses the role that different components of the academic strength of the secondary-school curriculum (i.e. "number," "subjects" and "grades" of advanced academic courses) play in explaining social origin differences in access to prestigious universities (but also to other higher education institutions) in Scotland and the USA. A central aim of the paper is to investigate whether the mechanism behind the studied patterns of inequality differs depending on the characteristics of each educational system. Our results show pronounced social class gaps in entering top higher education institutions in both Scotland and the USA. Academic curriculum plays an important role in explaining these social class differences in both countries. However, while in Scotland "type of subjects" taken at an advanced level is the strongest mediator for the identified social class differences, in the USA, "number" of advanced subjects is the strongest. Moreover, taking into account the three academic components combined entirely explains the social class differences in Scotland. Considerable inequalities which are not explained by the strength of academic curriculum remain in the USA.