The National Institute on Aging (NIA) conducts and funds research aimed at extending the healthy, active years of life.1 This mission distinguishes the institute from others that focus primarily on the study of specific organs and diseases. Over its 50 years, the NIA has supported clinical and behavioral research across a wide range of issues. In this Viewpoint we highlight multicomplexity and dementia, 2 areas where the NIA has made integral and distinctive contributions. We also discuss the NIA鈥檚 role in applying principles from behavioral economics to research designed to improve the health of older persons.