There is a void in evidence-based information for making informed decisions on how to optimize care for older adults, particularly those 80 years and over. Because older adults are vastly underrepresented in clinical trials, there is a dearth of information about the appropriate use of drugs in this population. Yet older adults have higher rates of comorbidities and simultaneous use of multiple medications than the general population, and are the majority users of many medications. Additionally, age-related physiological and pathological changes, particularly for adults 80 years of age and older, can lead to significant differences in the pharmacokinetics (PK)2 and pharmacodynamics (PD)3 of a given drug compared to the general population. On August 5 and 6, 2020, the National Academies of Sciences, Engineering, and Medicine hosted a workshop titled Drug Research and Development for Adults Across the Older Age Span. The workshop was designed to examine the challenges and opportunities in drug research and development for older adult populations, explore barriers that impede safety and efficacy studies in these populations, and share lessons learned for better understanding clinical pharmacology for populations over age 65. This publication summarizes the presentation and discussion of the workshop.