This textbook is a first major introduction to behavioral economics, designed primarily for advanced undergraduate students. Unquestionably the hottest new field to have emerged in the social sciences over the past decade, behavioral considerations are now making themselves felt across academia and beyond and books such as Richard Thaler and Cass Sunstein's Nudge have become blueprints for a new way of thinking. This text will introduce all the key concepts to a student audience. Although grounded in game theory and experimental economics, the focus of the text is very much on Behavior as opposed to Games. The field is presented as a coherent subject and the text covers a host of cutting edge developments including the analysis of fairness, reciprocity and altruism, as well as the brave new frontier of neuroeconomics.