Aging populations are generating both challenges and opportunities for societies around the globe. Increases in longevity and improvements in health raise many questions. What steps can be taken to optimize physical and cognitive health and productivity across the life span? How will older people finance their retirement and health care? What will be the macroeconomic implications of an aging population? How will communities be shaped by the shift in age structure? What global interconnections will affect how each society handles the aging of its population?