Apps explains why time-use data are essential for analyzing issues of gender equity and intrahousehold allocation of resources, comparing living standards, and estimating the behavioral effects of changes in policy variables. First, she shows that the neglect of these data in much of the literature on household behavior in both industrial and developing economies can be traced to unrealistic assumptions on domestic production and the mistaken idea that nonmarket time can be viewed as leisure. She argues that an approach is required that makes explicit the need for data on the time family members spend on domestic work as well as on labor supply. The author outlines an approach of this kind and uses it to identify the specialized assumptions that are used when they are missing. She also discusses the limitations of available time-use survey datasets that are due to deficiencies in survey design. The more serious and common problems are illustrated, using as case studies the Statistics South Africa 2000 Time-Use Survey and the time-use module in the Nicaraguan 1998 Living Standards Measurements Survey.