In January 2006 people dually eligible for Medicaid and Medicare, many of whom have serious mental disorders, were required to transition from Medicaid coverage for medications to Medicare Part D drug plans. Advocates have raised concerns about disruptions in medication regimens because of formulary exclusions and utilization controls. Because data for a full assessment of Part D's impact will not be available for some time, Julie Marie Donohue, Ph.D., and Richard Gabriel Frank, Ph.D., used data from several sources to estimate the level of disruption. They found that formulary restrictions on psychotropic medications were common among the drug plans they studied. Estimated rates of medication switching attributable to Medicare Part D were 6%—10% among beneficiaries using antipsychotics, 5%—7% among those using antidepressants, and 2%—4% among those using mood stabilizers. The authors concluded that relatively few dually eligible beneficiaries with mental disorders are likely to experience disruptions. However, beneficiaries in some plans will experience significant barriers to medication access (page 1285).