When and How Do Women Directors Matter for Corporate Sustainability? The French Case

This study examines when and how board gender diversity matters for corporate sustainability. Using a sample of French listed firms over 2006–2024, we combine dynamic system GMM estimations with difference‐in‐differences tests around France's phased board gender quotas. The results show that greater female board representation is associated with stronger ESG performance, but that this relationship is highly contingent. It becomes substantially stronger once women attain meaningful representation, with the clearest evidence emerging around 30% of board seats and approximately four women directors. Consistently, the 20% regulatory threshold produces no significant ESG effect, whereas the 40% requirement is followed by significant improvements among initially non‐compliant firms. Decomposing ESG performance reveals particularly strong associations with social performance, stakeholder engagement, and product responsibility, but a negative association with environmental innovation. Finally, the relationship is concentrated among financially stronger firms and firms with powerful CEOs. Overall, the findings show that the sustainability consequences of board gender diversity depend on representation, the ESG dimension considered, and organizational context.