Résumé : Low success rates in the first year of university remain a major challenge. To improve studentsuccess, a Belgian university implemented a targeted academic support program combining adiagnostic test assessing subject-specific skills with remedial courses designed to reinforcethese skills. This study aimed to measure the effectiveness of this program, using a propensityscore matching method to estimate the causal effect of participation in remedial courses onstudents’ academic achievement at the end of their first year at university. Based on data from1,038 first-year students identified as academically at risk through a diagnostic test, the resultsshow that students who regularly attended remedial courses succeeded better than comparablepeers who did not participate. The effect increased with the attendance rate, highlighting theimportance of sustained engagement in the support program. These findings provide strongevidence that early, targeted academic interventions can improve first-year outcomes amongunderprepared students in non-selective higher education contexts.