The survival of large segments of human populations to advanced ages is a crowning achievement of improvements in public health and medicine, but in the 21st century, our continued desire to extend life brings forth a unique dilemma. The risk of death from chronic fatal diseases has declined, but even if it continues to do so in the future, the resulting longevity benefits are likely to diminish. It is even possible that unhealthy life expectancy could rise in the future as major fatal diseases wane. The reason for this is that the longer we live, the greater the influence of biological aging on the expression of fatal and disabling diseases. Research in gerontology has already demonstrated that aging is inherently modifiable, and that a therapeutic intervention that slows aging in people is a plausible target for science and public health. Given the speed with which population aging is progressing and chronic fatal and disabling conditions are challenging health-care costs across the globe, the case is now being made that delayed aging could be one of the most efficient and promising ways to combat disease, extend healthy life, compress morbidity, and reduce health-care costs.