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. We also look at a variety of tools policy makers may use to effect change, highlight the role of trendsetters in social change, and the conditions under which they can be successful. 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. This is Part 1 of the Social Norms, Social Change series. In these lectures, I introduce all the basic concepts and definitions, such as social expectations and conditional preferences, that help us distinguish between different types of social practices like customs, descriptive norms and social norms. Expectations and preferences can be measured, and these lectures explain how to measure them. Measurement is crucial to understand the nature of the practice you are facing, but also whether an intervention was or was not successful, and why. In Part 2, we will examine social change, the tools we may use to enact change, and put into practice all we have learned in Part 1. All students who successfully complete the course requirements will earn a Statement of Accomplishment free of cost.