This is a course on social norms, the rules that glue societies together. It teaches how to diagnose social norms, and how to distinguish them from other social constructs, like customs or conventions. These distinctions are crucial for effective policy interventions aimed to create new, beneficial norms or eliminate harmful ones. The course teaches how to measure social norms and the expectations that support them, and how to decide whether they cause specific behaviors. The course is a joint Penn-UNICEF project, and it includes many examples of norms that sustain behaviors like child marriage, gender violence and sanitation practices.