The TRICARE Senior Supplement Demonstration (TSSD), conducted from March 2000 through December 2002, offers Medicare-eligible military beneficiaries the option of enrolling in TRICARE as a supplement to Medicare. This book describes RAND's evaluation of the TSSD program. Enrollment in TSSD was very low because of several factors, particularly the introduction of the permanent TRICARE for Life (TFL) that supercedes TSSD. However, implementation of TSSD as a permanent national program is feasible and would benefit many Medicare-eligible military retirees.