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.During the past century and a half, the living arrangements of the aged in the United States shifted dramatically. The dimensions of change are illustrated in Figure 1. In 1850, twothirds of whites age 65 or older lived with an adult child. The percentage of elderly whites residing with adult children declined steadily from 1850 to 1980, reaching a nadir of 13 percent in 1990 before rising slightly in 2000. Among blacks, the trend was less dramatic but still sizeable; coresidence fell from 50 percent in 1870 to 22 percent a century later. 1 The transformation of the living arrangements of the aged was equally dramatic among unmarried men, unmarried women, and married couples, although there was slight variation in the timing of change (Ruggles 2003).This article examines explanations for this remarkable simplification of U.S. family structure. I assess historical evidence from the census to uncover clues about the formation of intergenerational families and the incentives for both the older generation and the younger generation to reside together. I argue that scholars have overemphasized the effects of rising income of the older generation and underestimated the role of growing economic independence of the younger generation. More broadly, I argue that the decline of intergenerational coresidence reflects a decline of patriarchal control brought about by the rise of wage labor and the decline of agriculture.Direct correspondence to Steven Ruggles, University of Minnesota, Minnesota Population Center, 50 Willey Hall, 225 19th Avenue South, Minneapolis, MN 55455 (ruggles@umn.edu). The author is grateful for the comments and suggestions of Catherine Fitch, Miriam King, Carolyn Liebler, Evan Roberts, three anonymous reviewers, the editors of the ASR, and participants at several colloquia and the 2005 meeting of the...