Following calls to capture the consequences of family involvement in the business, this article empirically investigates the mediating role of board processes (i.e., effort norms, use of knowledge and skills, and cognitive conflicts) and board (control and strategy) tasks in the relationship between family involvement and firm performance in small and medium-sized companies. To address this purpose, we developed a theoretical model using family business and corporate governance literature. We collected data from one sample of small and medium-sized enterprises, and we applied structural equation modeling to validate and test constructs and relationships. Our results show that (a) family involvement in the business has a positive impact on effort norms and use of knowledge and skills, and a negative one on cognitive conflicts, (b) board processes have generally a positive influence on board tasks performance, and (c) board strategy task performance positively influences firm financial performance, while board control tasks do not have a significant impact. Results have implications for both research and practice.