One theme that emerges from the following analysis is that a tremendous amount of sorting takes place in the on-demand economy, and, by dint of their backgrounds, family circumstances, and other pursuits, Uber’s driver-partners are well matched to the type of work they are doing. Notably, Uber's driver-partners are attracted to the flexible schedules that driving on the Uber platform affords. The hours that driver-partners spend using the Uber platform can, and do, vary considerably from day to day and week to week, depending on workers’ desires in light of market conditions. In addition, most driver-partners do not appear to turn to Uber out of desperation or because they face an absence of other opportunities in the job market—only eight percent were unemployed just before they started working on the Uber platform—but rather because the nature of the work, the flexibility, and the compensation appeals to them compared with other available options. Even as the national unemployment rate fell to 5 percent, the number of active Uber drivers continued to rise. These findings likely relate to a broader, more generalized demand by many individuals for workplace policies that favor flexible work schedules, family-oriented leave policies, and telecommuting arrangements, over the standard nine-to-five work schedule, in order to support a more family-friendly lifestyle. Historically, independent contractors have reported in surveys that they prefer their working arrangements to traditional employment relationships, and this tendency appears to be continuing in the on-demand economy. Demand for work opportunities that offer flexible schedules is partly driven by the aging of the workforce and the increase in secondary earners, and it will likely increase as a result of ongoing demographic trends. Flexible work opportunities like Uber can also help workers smooth fluctuations in other sources of income (Farrell and Greig, 2016a). In addition, if changes to the health care system help reduce job lock—by making health insurance more readily available and accessible to individuals—more people are likely to become entrepreneurs and take advantage of the flexibility and income-generating potential made possible by the on-demand economy. For these reasons as well, it is critical to understand how the on-demand economy is affecting work opportunities. This paper provides a step toward understanding the nature of work in the on-demand economy by reporting new evidence on hours of work, income, and the motivations and backgrounds of participants in one of its important segments, driver-partners using the Uber platform. The next section provides a brief overview of the literature on contingent and alternative work arrangements as context for the growth of Uber. The second section draws on the BSG data to describe the backgrounds and motivations of Uber driver- partners. The third section utilizes anonymized, aggregated administrative data to describe the driving histories, schedules, cross-city growth rates, and earnings of Uber driver-partners. The final section concludes and suggests directions for further research. 3