The Federal Employees Health Benefits Program is the nation's largest employer-sponsored health plan, offering enrollees numerous options for health insurance. The program has long kept participation high, administrative costs low, and premiums affordable-making it an enticing model for health reformers of all political stripes. Most curent federal reform proposals include a similar insurance "exchange" to offer a range of private-market insurance choices to a broader population. While opening the FEHBP to non-federal employees or replicating its features nationally is not feasible, program experience suggests lessons about benefits design, relations with participating health plans, and avoiding adverse selection in enrollment.