Many youth leave school early without an upper secondary education, impeding their chances in the labor market. Early school leavers come disproportionately from families with low parental education. In some countries, there are alternative routes to upper secondary qualifications as adults. Does adult attainment reduce initial social differences in educational attainment, or does it reinforce such differences? Norway is one of the countries where many attain upper secondary qualifications in adulthood. Using individual data from administrative registers, we follow five Norwegian birth cohorts (1973–1977) from age 20 to 40. We document that the association between parental education and upper secondary completion declines monotonically with age, ending at age 40 about 35% below that at age 20. We also document that the alternative routes to adult qualifications recruit students of different family backgrounds. In particular, adults who acquire vocational qualifications via the experience-based route come from families with lower education than other groups. Our evidence suggests that institutions that offer opportunities for certifying qualifications acquired at work mitigate social gradients, fostering more equal opportunities within the education system.