This book explores diversity in boardrooms to highlight the link between the heterogeneous dimensions of board diversity and their impact on the firms. The book provides a brief definition of corporate governance and focuses on the role and functions of the board of directors. The work contributes to the literature enriching the empirical findings about board diversity. After a deep review of the literature within several theoretical frameworks, such as agency, stakeholder, stewardship, resource dependence, and the institutional theory, the focus moves on the impact on financial performance. The board diversity effects are tested through an empirical analysis conducted on a sample of European listed companies, performing both a single and a joint diversity index analysis. Practitioners and academics will find this book particularly timely and useful as it combines both a review of the literature and robust empirical investigation. It will be an excellent reading for academics and practitioners interested in firm performance, corporate governance and stakeholder theory.