Résumé : This article provides first evidence on whether corporate social responsibility (CSR) influences the productivity effects of overeducation. By relying on detailed Belgian linked employer-employee panel data covering the period 1999-2010, our empirical results exhibit a positive and significant impact of over-education on firm productivity. Moreover, they suggest that the effect of over-education is positively enhanced when the firm implements a corporate social responsibility process, especially when it aims to have: i) a good match between job requirements and workers’ educational level, ii) a diverse workforce in terms of gender and age, and iii) a long-term relationship with its workers. Whenfocussing on required and over-education, the results suggest that CSR, besides representing an innovative and proactive approach for the firms’ stakeholders, may also be beneficial for the firm itself through a bigger increase in productivity for each additional year of required or over-education.