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 new method for measuring, comparing, and analyzing the relationship between happiness and the way people spend their time - across countries, regions, and history - this book will help set the agenda for research. It does so by introducing the system of National Time Accounting (NTA), which relies on individuals' own evaluations of their emotional experiences during various uses of time, a distinct improvement in measuring well-being from objective measures such as the Gross National Product. A distinguished group of contributors here summarize the NTA methodology, provide illustrative findings about happiness based on NTA, and subject the system to a rigorous conceptual and methodological critique that only strengthens the approach. As subjective well-being is topical in economics, psychology, and other social sciences, this book should have cross-disciplinary appeal.