In 1980, behavioural economics did not exist as a field. Most economists were deeply skeptical about importing insights from psychology into their discipline. In 2003, behavioural economics is virtually mainstream, and behavioural economists, including several contributors to this volume, have garnered some of the profession's most prestigious awards. This book assembles 25 of the most important papers in the area published since around 1990. Among them are many that update and extend earlier foundational contributions, as well as cutting-edge pieces that break new theoretical and empirical ground.