This research-based essay argues, as a stimulus to Forum discussion, that our currently age-differentiated society will give way to an age-integrated one. Age will lose its power to constrain people's entry, exit, and performance in such basic social institutions as education, work, and retirement. Revolutionary changes toward age integration are needed to reduce the "structural lag," in which the dynamism of human aging is outpacing the dynamism of structural change. To guide these changes, aging research is beginning to complement existing knowledge about human lives with new and deeper understanding of the social structures which shape and are shaped by these lives.