This book intends to develop a theory of the performance of organizations and nations that takes in consideration the culture of family and society. At an organizational level, the book explains why and how the behavior and performance of a firm are a function of the family culture of the firm’s founders. At a national level, the book argues that nations are exposed to cultural competition where nations of similar cultures compete against each other. The book investigated the political system of 17 nations and the economic system of 41 nations and found that family, non-family, and state modes of governance best fit nations competing in traditional, modern, and postmodern societies, respectively. A key implication of this book is that the cultural fit among systems of different levels (i.e., the family, organization, nation, and society) is a key factor in creating and sustaining a competitive advantage. By stressing such an implication in this book through building and testing a theory of the cultural fit among systems of different levels, decision makers, researchers, and practitioners will be able to enhance their roles.