This issue brief provides benchmarks, based on empirical analyses of 2002 data, for evaluating the quality of pharmaceutical care under the Medicare Part D prescription drug benefit. The analyses cover all major classes of pharmaceuticals used by beneficiaries with one of eight chronic conditions. Common patterns observed include: 1) a mounting disease burden is associated with increasingly complex medication regimens in every group, and 2) the intensity and persistence of drug use tend to rise with disease burden up to a point, before declining for beneficiaries with the greatest morbidity. The study concludes that neither traditional drug quality indicators nor new quality assurance mechanisms mandated by law are well aligned to capture suboptimal medication use at either end of the spectrum of disease burden in the Medicare population. A holistic approach to medication management is needed to ensure that Part D plans meet beneficiaries and policymakers' expectations for high-quality care.