The last several decades have seen major advances in the ways in which public economists investigate behavioural responses to taxation. Recent research has utilized new data sets and has applied new empirical methods, including laboratory experiments and natural and controlled field experiments. The application of behavioural economics has contributed insights from other disciplines, especially psychology. Here James Alm and Sebastian Leguizamon discuss the lessons from all this work. Covering such topics as labour supply, charitable giving, savings, capital gains realisations, mobility, bequests, family structure, reported income and tax evasion, they highlight the current state of knowledge in this area. They present new thinking about the relevant issues and an analysis of useful policy options.