Using a sample of 76 Italian publicly listed firms for the year 2019, this paper investigates the association between the presence of a critical mass of women directors on the board and the firm’s CSR performance. It also examines whether the family firm status moderates this association. The OLS regression analysis shows that the presence of a critical mass of female directors positively influences the CSR performance. In addition, the empirical analysis shows that the family firm status has a negative direct effect on CSR performance, but has a positive interaction effect with a female critical mass. Overall, these findings support the conclusion that the effect of female directors on CSR performance is influenced by the family ownership structure. This finding contributes to both the literature on board gender diversity and to the literature on family firms by providing evidence on the role of family ownership as a contingency variable that positively moderates the effect of a critical mass of female directors on CSR performance. With regard to practical implications, this research calls the attention of board nomination committees on the key role of appointing a critical mass of female directors for achieving a better CSR performance.