Two powerful demographic processes—the falling birth rate and increasing life expectancy—are reshaping the US population. Longer life expectancy leads to a healthier population, greater capacity to work, and a more active lifestyle, but it also raises the share of the population over age 65—a traditional measure of population aging. This measure overstates aging problems and leads policymakers to misallocate government resources. We construct alternative population aging measures based on the share of the population whose life expectancy is less than a certain number of years. These measures indicate that the population is aging much more slowly than conventional measures indicate.