This article describes the creation of the National Institute on Aging at the National Institutes of Health, as a case study in “agenda-building” (a theoretical concept used to explain why some issues receive official attention from the public and its leaders, while others, often equally critical, do not). The issue of federal support for research on aging, which led to a specific demand for a separate institute, was initiated by a small group of biomedical scientists. But it reached agenda status only after an effective coalition of lay and professional groups gave support to the issue. This coalition was interested not only in biomedical, behavioral, and social aspects of aging, but also in socioeconomic concerns related to the rapidly increasing elderly population. The nature and purpose of the institute was greatly influenced by the political forces and social conditions which brought it into existence. This case study illustrates how biomedical research policy evolves when the federal government fails to take the lead in developing an overall strategy, not only for research on aging, but also for all areas of biomedical research.