These studies are based on information on time use in nine countries. Such studies will become more common as more governments fund time-budget surveys and as economists realize the benefits of using this type of data. Each does something that either could not have been accomplished at all, or that could have been done much less convincingly on the data that one typically obtains from households. Part I deals with the "when?" and "with whom?" questions describing human behavior. These questions have been essentially ignored by social scientists generally, and have been completely ignored by...