Surely everyone wants to know the source of happiness, and indeed, economists and social scientists are increasingly interested in the study and effects of subjective well-being. Putting forward a rigorous method and new data for measuring, comparing, and analyzing the relationship between well-being and the way people spend their time - across countries, demographic groups, and history - this book will help set the agenda of research and policy for decades to come. It does so by introducing a system of National Time Accounting (NTA), which relies on individuals' own evaluations of their emotional experiences during various uses of time, a distinct departure from subjective measures such as life satisfaction and objective measures such as the Gross Domestic Product. A distinguished group of contributors here summarize the NTA method, provide illustrative findings about well-being based on NTA, and subject the approach to a rigorous conceptual and methodological critique that advances the field. As subjective well-being is topical in economics, psychology, and other social sciences, this book should have cross-disciplinary appeal.