Two-thirds of Canadian adults have post-secondary credentials, ranging from trade certificates to bachelor’s and advanced degrees. Yet, little is known about health across these levels, partly because the extensive literature on the education–health gradient has often grouped all post-secondary credentials into one or two broad categories. This is an important gap because it obscures social stratification at the post-secondary level. We provide the first comprehensive study of health across educational attainment levels in Canada, focusing on detailed post-secondary credentials. Data from the 2014–2016 Canadian General Social Survey for adults aged 25 years and older are used to assess self-rated health as a function of educational credentials for the total population and major population groups in relative and absolute terms, and to examine potential mechanisms that could explain the observed patterns. Analyses reveal substantively large, statistically significant differences in health across post-secondary credential levels: the predicted probability of reporting very good or excellent health is 49 percent among adults with trade certificates but 66 percent among those with advanced degrees. Such differences are evident in most although not all population groups. Taking into account social, economic, health–behavioural, and other covariates attenuates the post-secondary credential–health gradient by about 60 percent. Our findings highlight the importance of stratification in post-secondary credentials and the resulting health disparities. Understanding the reasons and implications of these disparities is important for educational, health, and social justice policies.