Lower birth rates and increasing life expectancy are dramatically changing the population’s age distribution, in the U.S. and around the globe. With fewer younger people and more older people, “top-heavy” societies present serious challenges to families, communities, and nations as a whole. Two challenges that have received most attention are economic security and health care, especially long-term care, among the older adult population. These two issues are clearly grand challenges; and most discussions about population aging have focused on these challenges because of their complexity and seriousness. Another grand challenge comes as a response to these demands of population aging. How can we shape social policies and programs to optimally engage the growing human capital of the aging population, for the sake of society and older adults themselves? As health, education, and economic security have generally increased with each generation to date, so has the capacity of individuals to initiate and continue productive activities longer into the life course. “Productive aging” puts forward the fundamental view that the capacity of older adults must be better utilized in activities that make economic contributions to society—working, volunteering, and care giving. This engagement can lead to multiple positive ends: offsetting fiscal strains of a large older population, contributing to the betterment of families and civil society, and maintaining the health of older adults. Yet ageist attitudes and outdated social structures limit participation of older adults in these important social roles as well as prevent the optimization of outcomes for older adults, families and society. The grand challenge is increasing the productive engagement of older adults, while maximizing outcomes for society as well as older adults themselves. More specifically, the challenges are: changing work environments and employment policies to enable people to work longer, restructuring educational institutions so that individuals can educate themselves across the life course, enabling older adults to engage in volunteer and service work; and supporting care giving to facilitate involvement and reduce negative effects.