Over the past century, we have explored the solar system, split the atom, and wired the earth, but somehow, despite all of our technical prowess, we have struggled to understand something far more important: our own cultural differences. Observing the wide variety of cultural permutations, people assumed for centuries that there were as many explanations for these permutations and rifts as there were examples of them. Michele Gelfand’s research shows that many cultural differences reflect a simple, but often invisible distinction: The strength of social norms. Tight cultures have strong social norms and little tolerance for deviance, while loose cultures have weak social norms and are highly permissive. The tightness or looseness of social norms turns out to be a Rosetta Stone for human groups. It illuminates similar patterns of difference across nations, states, organizations, social class, and households. It is also a global fault line: many of the conflicts we encounter spring from the structural stress of tight-loose tension. By unmasking culture to reveal tight-loose dynamics, we can see fresh patterns in history, illuminate some of today’s most puzzling trends and events, and see our own behavior in a new light. At a time of intense political conflict and rapid social change, this template shows us that there is indeed a method to the madness, and that moderation – not tight or loose extremes – has never been more needed.