The study examines gender diversity in a sample of Italian listed companies. Specifically, we study the effect of the percentage and the role of women directors in the boardroom in affecting firm performance. Using data from Italian listed firms during the period 2006–2015, the aim is to show the effect arising from the introduction of Italian Law 120/2011, which forces the listed companies to reserve a mandatory quota for female directors on the board. The results show that increasing the percentage of female directors leads to superior financial performance. However, focusing on the roles of female directors, we observe that the percentage of executive female directors is not correlated with firm performance. Diversely, companies with a higher percentage of independent female directors are associated with better firm performance.