Effective health care is a core determinant of successful aging, and medications are one of the most important therapeutic tools of health care providers. Most older adults use at least one prescription drug. Costs for these drugs are a substantial out-of-pocket expense for Medicare beneficiaries, and low-income older adults must weigh these costs against those of other basic needs. Although medications bring welcome relief to millions of elderly persons with age-related conditions, adverse drug events are an important cause of illness and death in these patients. Thus, the appropriate, cost-effective use of medication is central to successful aging. Despite increasing attention to geriatric pharmacotherapy, there is an enormous need for additional research to improve the use of medications among older adults. The necessary research agenda encompasses much more than just the discovery of new drugs; better use of the current pharmacopeia has great potential to improve the lives of older adults. We review four domains of pharmaceutical research: drug discovery and delivery, drug efficacy and safety, pharmacoepidemiology and drug policy, and improved access to and use of drugs. These domains encompass both the pre- and postmarketing phases of drug research. Premarketing research currently has greater magnitude and a better infrastructure than postmarketing research, yet issues arising in the two phases of research are equally important to the health and safety of older adults. A national, federally supported pharmaceutical database could greatly enhance the infrastructure of postmarketing research. However, many major improvements in medication use among older adults will also depend on closing the gap between knowledge and practice and increasing the ability of older adults to manage their medications.