Under the Medicare Prescription Drug, Improvement, and Modernization Act of 2003 (MMA), dual-eligible beneficiaries--individuals with both Medicare and Medicaid coverage--have their drug costs covered under Medicare Part D rather than under state Medicaid programs. The MMA requires the Centers for Medicare & Medicaid Services (CMS) to enroll these beneficiaries in a Medicare prescription drug plan (PDP) if they do not select a plan on their own. CMS enrolled about 5.5 million dual-eligible beneficiaries in late 2005 and about 634,000 who became dually eligible during 2006. GAO was asked to testify on (1) CMS's process for enrolling new dual-eligible beneficiaries into PDPs and its effect on access to drugs and (2) how CMS set the effective coverage date for certain dual-eligible beneficiaries and its implementation of this policy. This testimony is based on the GAO report, Medicare Part D: Challenges in Enrolling New Dual-Eligible Beneficiaries (GAO-07-272).