Publisher Summary The goal of this chapter is to present a conceptual framework to approach health problems of aging, to provide examples of how research studies of aging build on this conceptual framework, and to address aspects of research design, which can be modified to promote broader age participation and to specifically address unique problems of aging. Since older adults have high rates of health problems and are the most frequent users of healthcare, clinical research to build the knowledge base for care of the aged is essential. Without efforts to change the way one performs research, one will continue to mistakenly extrapolate information from studies in younger adults to decisions about care of the aged. Investigators can incorporate general concepts about aging processes into research questions and study design. Many practical solutions exist that can foster increased participation of older adults in research studies. Better knowledge about health and aging can result in important new insights into fundamental biological processes, better care, and more rational use of healthcare resources, and ultimately into improved quality of life and function for older adults. Most chronic conditions, including heart disease, lung disease, diabetes, hypertension, kidney disease, cancer, and arthritis, are two to ten times more common in persons aged 65 and over compared to younger adults. Consequently, multiple coexisting conditions are much more likely in older than younger adults. Older adults have high rates of health problems and are the most frequent users of healthcare. Clinical research to build the knowledge base for care of the aged is essential.