This is a print on demand edition of a hard to find publication. Contents:(1) Overview of the Medicare Prescription Drug Benefit Program: Design of the Medicare Prescription Drug Benefit; Distribution of Spending in Medicare Part D; The Role of Private Plans in Medicare Part D; (2) Generic Drugs in Medicare Part D: Generic Substitution; Therapeutic Substitution; Comparing Potential Savings from Generic and Therapeutic Substitution; (3) Implications of Future Developments: First-Time Generic Entry; New Brand-Name Drugs; Biologics. (4) Appendix: Description of Data Used in This Analysis. Charts and tables.