Population aging strains social insurance and pension systems and challenges existing models of social support. It affects economic growth, trade, migration, disease patterns and prevalence, and fundamental assumptions about growing older. Using data from the United Nations, U.S. Census Bureau, and Statistical Office of the European Communities as well as regional surveys and scientific journals, the U.S. National Institute on Aging (NIA), with input from demographers, economists, and experts on aging, identified nine emerging trends in global aging. Together, these trends present a snapshot of challenges and opportunities that clearly show why population aging matters.