This article analyses how board structure can affect both financial and social performance, comparing family and non-family firms. Our theoretical framework is based on the integration of the agency theory, traditionally used in the analysis of the impact of the board on the firm’s financial performance, with the stakeholder theory, which is more appropriate in the analysis of the social aspects of the firm. Three main aspects are addressed: the analysis of the firm’s social performance; the integration of agency theory with stakeholder theory; and the study of the specific characteristics of family firms’ boards. The research confirms that neither the agency theory nor the stakeholder theory is fully able to explain on its own, without the other, the link between board structure and firm performance. The article has both practical and theoretical implications for the firm’s activities and increases our knowledge about the relationship between the board and firm performance.