If we can measure how the members of a society spend their time, we have the elements of a certain sort of account of how that society works. This is what Jonathan Gershuny provides in Changing Times, using 120,000 survey-diary accounts of daily life in twenty countries from the 1960s on to construct an account of how time-use patterns have changed in the developed world over the last third of a century and to relate these changes to economic development. His analysis of the data and of existing theoretical approaches highlights, and goes some way to addressing, problems in the standard National Accounting classifications of work and will become the foundation of a new approach to the economics and sociology of time.