This book offers a course in behavioural economics at the upper undergraduate and graduate level. Behavioural economics has quickly become popular, both within economics and among policy makers. This book reflects an open-minded approach towards economics, open to insights from other disciplines and new ways of data collection and analysis. It helps economists to build more realistic models of decision making and policy makers to more successfully implement policy. It gives an overview of recent developments in behavioural economics stressing throughout how behavioural economics can be applied in important policy decisions with a special focus on health policy, as well as examples from finance, insurance, and environmental policy and climate change. The book pays particular attention to current open questions, thereby developing students' critical faculties. It gives students tools and insights to understand the current literature, to perform behavioural economics analyses, and to offer well-founded policy advice.