An insightful and entertaining look into the psychology of why people in different cultures think and act differently. Michele Gelfand describes tight (Japan, India) and loose (Brazil, New Zealand) cultures, that is, tight or loose in how norms are felt and enforced. Tight norms develop in societies facing threats. Diversity (if not extreme), mobility, and an absence of threats can pull a culture toward looseness. Intriguingly, the same tight-loose logic that explains differences across nations also explains differences across states, organizations, social classes, and households.