This chapter offers an overview of the evolution of research on boards of directors over the last three decades. The concurrent emergence of multi-theoretical views alongside more nuanced and rich methodological approaches has significantly enhanced our understanding of how boards and directors behave. The chapter introduces the key research questions, objectives, methods and results of early research on boards, the so-called input–output studies dominating the 1990s. Next, it discusses the main limitations of these studies and their mixed and heterogeneous findings. Then, it discusses the growing interest in “opening the black box” of boards dynamics, and synthetizes several ongoing research projects aiming to offer a more nuanced understanding of board processes. Last, it summarizes the key findings of studies on boardroom dynamics and effectiveness and outlines some avenues that may inspire future research by governance scholars and the development of best practices by practitioners.