The overall aim of the project is to evaluate the role of enhanced plans in the Medicare Part D market. The project will 1) quantify the enrollment growth in enhanced plans relative to basic plans; 2) evaluate the characteristics of enrollees by plan type; 3) evaluate the benefits of enhanced plans currently and historically; and 4) assess the impact of enrollment growth in enhanced plans on the integrity of the Part D competitive bidding program, which is currently based on the design of the basic benefit. Data sources include CMS Part D Contract and Enrollment data, Medicare claims data, and the CMS plan payment data.