["Population and Development Review, Volume 47, Issue 2, Page 475-503, June 2021. ", "\nAbstract\nDisparities in reproductive behavior visible in the developed world are a long‐term implication of the demographic transition. While present at the very outset of the transition, their effects are most visible once childhood mortality loses its relevance as a key constraint on reproduction. These disparities are rooted in the type of society that emerged as the result of the way the historical role of the family and individual in society interacted with social and economic modernization processes characterizing the entire century, but especially visible during the rapid acceleration of social and cultural changes after mid‐century. The way these new societies function provides a necessary backdrop for understanding fertility in a world of individual reproductive choice and competing goals. The result is that traditionally individualistic societies tend to fare better than societies where family loyalties are and have always been a cornerstone of society. Disparities in fertility are rooted in the incentives and disincentives for reproduction present in society, are unlikely to disappear anytime soon and are leading to very different rates of aging in the developed world.\n"]