Abstract
OBJECTIVES: Population aging is reshaping life courses. This article examines how extended longevity and the collective experience of aging societies alter the timing, meaning, and structure of life course transitions. It explores how individuals adapt their behaviors, expectations, and intergenerational roles to these shifts, and how aging at the micro-level is embedded within macro-level demographic and institutional transformations. METHODS: Drawing on conceptual and empirical insights from the Age-It Research Program, alongside state-of-the-art gerontological and sociodemographic literature, the article adopts a life course perspective informed by the principles of timing and linked lives. RESULTS: Population aging transforms the life course in at least three fundamental ways. First, increasing longevity and improved health have opened a new stage of life after retirement. Second, delayed transitions in education, work, and family formation are emerging as adaptations to longer lives, though they generate tensions with unchanged biological limits to fertility and evolving intergenerational expectations. Third, family structures are becoming increasingly "beanpole"-longer but thinner-reshaping intergenerational solidarities and increasing the relevance of extended- and non-kin ties. DISCUSSION: The increase in longevity is not merely stretching life but fundamentally redefining it. Growing old in an aging society becomes both a new individual experience and a collective transformation that challenges the adequacy of traditional life course categories. The Age-It findings call for conceptual renewal to better capture new stages, shifting chronologies, and reconfigured solidarities. Population aging also reshapes the research agenda of gerontologists.