This course could be thought of as the science of decision making and behavior change. Over the last 30 years, psychologists and economists have gained a deeper understanding of what motivates people, how they process information, and what non-economic features of the choice environment influence decisions. Many of their insights challenge traditional assumptions about rationality and self-interest. This research program (sometimes called "behavioral economics" or "behavioral science") has provided insights into how people's decisions deviate from "optimal" choices as well as the consequences of such deviations. This course is devoted to understanding the nature, causes, and implications of these human cognitive and behavioral tendencies. There are three objectives. First, we aim to help you better understand the science of human thinking borrowing from social psychology, cognitive psychology, political science, organizational behavior, decision science, and economics. Second, we aim to train you to design policies and interventions that improve societal well-being by leveraging these insights about human decision making (i.e., develop "nudges"). Third, this course aims to improve the quality of your own judgments and decisions. Applications of the material covered will include policy design, negotiation, risk management, institutional design, financial markets, human resource management, organization of teams, policy analysis, and political movements, among others.