Scientists who study aging now generally agree that it is malleable and capable of being slowed. Rapid progress in recent years toward understanding and making use of this malleability has paved the way for breakthroughs and interventions that will increase human health in later life by opposing the primary risk factor for virtually every disease we face as we grow older—aging itself. Better understanding of this “common denominator” of disease could usher in a new era of preventive medicine, enabling interventions that stave off everything from dementia to cancer to osteoporosis. Poised as we are for an unprecedented aging of our population and staggering increases in chronic age-related diseases and disabilities, even modest extensions of healthy lifespan could produce outsized returns of extended productivity, reduced caregiver burdens, lessened Medicare spending, and more effective healthcare in future years. The field of aging research is poised to make transformational gains in the near future. Few, if any, areas for investing research dollars offer greater potential returns for public health.