It is well researched that people with lower education are more likely to become ill and die at an earlier age than those who are well educated. We, however know much less about the mechanisms which bring this about, especially the contextual factors. One way to obtain new information is to compare countries with similar features and focus on institutional factors such as the welfare state's organization. For health outcomes, the framework of the healthcare sector is highly relevant, but it has thus only been explored to a limited extent by comparative welfare state research. The present study places the main explanatory variable at the contextual level, particularly the institutional structure of the welfare state. The role of primary care quality for moderating the relationship between education and self-rated health will be empirically tested by comparing 24 affluent countries. Data from the European Social Survey (ESS) round 1 to 9, years 2002 to 2018, is pooled and matched with data on primary care quality from the Organization for Economic Cooperation and Development (OECD). The results lend support to the contention that primary care quality reduces the educational gradient in health and that the moderating effect of primary care depends on age. Respondents with low education were shown to benefit from improved primary care quality already as young adults, while for respondents with higher education, such an effect is found only amongst middle-aged and older adults.