Despite congressional directives calling on federal agencies to promote part-time employment opportunities, the civil service uses part-time workers far less than does the private sector The reason may lie both in decreased career advancement for part-timers and in higher administrative costs for federal agencies. Using two large samples of federal employees, the author explores differences between part-time and full-time employees in terms of their characteristics, career patterns, work satisfaction, and productivity. Although part-timers hold lower grades and are promoted more slowly than comparably educated and experienced workers of the same sex, they are as satisfied with their jobs and pay as are full-time workers and more satisfied with their work-family balance. Their higher turnover rates and some evidence of lower performance ratings suggest that federal agencies may continue to resist expansion of part-time employment.