In this article, first, we present new evidence on a specific type of compensatory advantage (CA) mechanism in educational transitions and attainment, whereby students from socio-economically advantaged families compensate the negative event of achieving poor grades by ignoring them and disproportionally moving on to the next level of education. Using two independent data sources, we focus on the attainment of an upper secondary degree and the transition from high school to university in Italy, investigating the role of parental education and social class in compensating for an early poor academic performance. Second, we develop a simulated scenario analysis to assess how much of the observed social background inequality is due to the educational outcomes of poorly performing students from high social backgrounds. The results are consistent with the notion that a CA mechanism is in place and show that the advantage of individuals with higher backgrounds over those from lower backgrounds is much larger among students with bad marks in earlier school stages. We estimate that at least one-third of the observed social background inequality in educational transitions in Italy can be attributed to the CA mechanism. This result is consistent across different outcomes, samples and birth cohorts, and is robust to a number of sensitivity checks.