In the mid-nineteenth century, almost 70 percent of persons age 65 or older resided with their adult children; by the end of the twentieth century, fewer than 15 percent did so. Many scholars have argued that the simplification of the living arrangements of the aged resulted primarily from an increase in their resources, which enabled increasing numbers of elders to afford independent living. This article supports a different interpretation: the evidence suggests that the decline of coresidence between generations had less to do with the growing affluence of the aged than with the increasing opportunities of the younger generation. Using data from the Integrated Public Use Microdata Series (IPUMS), I examine long-run trends in the characteristics of both the older and the younger generations to gain insight into changing motivations for coresidence. In particular I investigate headship patterns, occupational status, income, and spatial coresidence patterns. I also reassess the potential impact of the Social Security program. I conclude that the decline of intergenerational coresidence resulted mainly from increasing opportunities for the young and declining parental control over their children.