Family firms represent the most prevalent organizational form worldwide, central to employment, innovation, and long-term value creation. This volume reviews the theoretical and empirical foundations of family business research, focusing on agency theory, socioemotional wealth, and long-term orientation. It examines firm performance, earnings quality, disclosure practices, governance, investment, and M&A strategies, as well as resilience during crises and succession challenges. By synthesizing regularities and contradictions across studies, the book highlights methodological frontiers and future directions related to sustainability, ESG disclosure, and internationalization.