With the article in this issue of JAGS by Mody et al.,1 we initiate an important new series on clinical aging research methods. Older adults are more likely to suffer from multiple diseases, take more medications, undergo more procedures, and use more health care than any other age group,2,3 yet the evidence base for care of the older adult is frequently derived from studies of younger, less complex populations.4–8 This discrepancy between the evidence and the population to which it is applied can be attributed to numerous conceptual and pragmatic challenges in clinical research methodology. Clinical investigators within and beyond the field of geriatrics have developed new approaches and creative strategies to overcome such challenges, but these solutions are often not explicitly presented in research manuscripts and are not widely known. One of the core missions of the American Geriatrics Society (AGS) and the Journal of the American Geriatrics Society (JAGS) is to promote evidence based care for older adults that results in better quality of life and functional independence.9 Thus, it is incumbent on us to disseminate knowledge that will help to generate that evidence. The goal of this new research series is to examine the ways that clinical research methodologies create barriers to increasing the evidence base for care of the older adult and to describe solutions based on thoughtful application of new and emerging research concepts and practices. Traditionally, the standards for rigorous research and evidence were designed to elucidate the causes and treatment of isolated diseases. These traditional design assumptions do not work well in aging, and alternative approaches are needed.10 The focus of the research question changes as chronic illnesses accumulate and interact with aging; healthcare research must incorporate new paradigms to understand the underlying contributors to disease,11 multisystem problems such as geriatric syndromes,12 and the importance of outcomes such as function and quality of life.13–15 The new concepts and approaches developed by clinical investigators in the field of aging permit study of this broader and more-relevant range of research questions and increase the repertoire of methods to manage the complexity of including older adults in research. We hope that the articles in this series will be useful to healthcare providers, investigators, health professions trainees, proposal reviewers, grant sponsors, and policy makers, all of whom depend on the creation and use of evidence to provide the best care to older adults. Each article in this series will focus on a type of challenge or barrier in clinical aging research. Using examples from the literature, the article will explain how the problem affects the creation of evidence and will present a repertoire of established and novel strategies to prevent or manage it. Several of the articles will be based on the Research Issues and Methods symposia presented at the annual meeting of the AGS and sponsored by the AGS Research Committee. In addition, JAGS invites authors to submit original articles that are responsive to the goals of the series. As the demand for care of older adults continues to increase, so will the demand for evidence to guide that care.16 We hope that this new series on challenges in clinical aging research will contribute to the continued growth of that evidence.