In this monograph, we discuss the corporate governance of business groups (BGs). To this end, we broadly define both BGs and corporate governance to provide an interdisciplinary conceptualization. We begin by reviewing the key governance theories that scholars have applied to BGs thus far. We then examine the different corporate governance dimensions (ownership, boards of directors, top-management teams, external control mechanisms, and sustainability-related issues) across the different types of BGs. As a result, we identify what we know about these organizations' corporate governance mechanisms. We close with a detailed discussion of fruitful areas for future research on BG corporate governance based on the gaps we identify.