The National Defense Authorization Act for Fiscal Year 2000 established the authority for a demonstration program under which eligible military retirees and their dependents would be permitted to enroll in the Uniformed Services Family Health Plan (USFHP) at any time, rather than during a designated 30-day period each spring. The USFHP Continuous Open Enrollment demonstration was conducted at three of the seven USFHP sites, beginning in early 2000. This book assesses the likely impact of continuous open enrollment on beneficiaries, the DoD, and other stakeholders. The authors interviewed USFHP and DoD staff and other key participants involved in rate-setting negotiations, visited each demonstration site, conducted focus groups with enrolled and eligible non-enrolled beneficiaries, and analyzed data on enrollment patterns. The evaluation found no apparent drawbacks for beneficiaries of the continuous open enrollment policy, nor any evidence that it increased enrollment in USFHP. For beneficiaries under age 65, the authors found that a de facto policy of continuous open enrollment already exists because beneficiaries may enroll in TRICARE Prime and then transfer to USFHP at any time. Finally, the authors expect the financial risk to the DoD to be minor, mainly because the current system of calculating payment rates places most risk from adverse selection on the USFHP. The authors recommend that the continuous open enrollment policy be extended to all USFHP sites and be made permanent.