BACKGROUND Marriage is a central institution for social reproduction in East Asia. Until the 1970s and 1980s, marriage across much of East Asia was early and universal. In recent decades, though, this pattern has begun shifting to one of later and less marriage. OBJECTIVE We explore the long-term implications for universal marriage patterns of future demographic change in marriage markets in the context of prevailing marriage norms by projecting trends in late singlehood (ages 45 to 49) in four East Asian societies (China, South Korea, Taiwan, and Japan). METHODS We estimate forces of attraction to characterize marriage matching norms by age and education across these different societies by drawing on large-scale population data. Next, we develop counterfactual scenarios in which we apply contemporary norms to future population structures in these societies, as well as scenarios based on more gender