I use data from the BLS' Employment Cost Index (ECI) Program to document differences in compensation between part-time and full-time jobs. The design of the ECI survey allows me to compare wage and nonwage compensation in jobs from the same establishment and occupation, but where one job is part-time and the other job is full-time. I find that compensation per hour is substantially lower in part-time jobs than in full-time jobs, even when the jobs are from the same establishment and occupation. Supplementary results using data from the Current Population Survey suggest that human capital differences between part-time and full-time workers explain at most a minority of the large difference in expected compensation. Therefore, the results suggest that an individual can expect a lower wage rate if he or she decides to work part-time rather than full-time, and much lower benefits per hour.