The general understanding of living arrangements of Korean-born immigrant elders is based on the popular American myth that immigrants from Asian culture tend to live together because they value living together. However, this study focuses on the importance of practical needs of elderly widows and their adult children in determining of residential status of elderly widows. The purpose of this study is to examine the relationship between elderly widows' needs, adult children's needs, familism values as a traditional value, and living arrangements among Korean-born immigrant elderly widows in the U.S. Structured interviews of 103 Korean-born immigrant elderly widows were conducted. This study included only elderly widows; therefore, the assessment of adult children's familism values and needs was based on their elderly mothers' perceptions. From environmental press theory, need contingent exchange theory, and previous studies, daycare needs of adult children, economic needs and health needs of elderly parents, and social-emotional needs of both were identified. The relationship between age of elderly widows and co-residence was linear in this sample, showing that as elderly parents became older, the percentage of co-residence within each age group decreased. It was found that adult children's total needs had interacted significantly with age of elderly widows in influencing living arrangements while elderly widows' total needs did not have a significant interaction effect with age of elderly widows. While higher elderly widows' total needs were associated with higher rates of co-residence irrespective of elderly parent's age, higher adult children's total needs were associated with higher rates of co-residence among the young-old (age 60-69) and old-old (70-79) groups than the oldest-old (80 and above) group. Lastly, familism values of elderly widows and adult children as perceived by elderly parents were not related to the likelihood of co-residence when needs variables were controlled. Overall, the results showed that the greater elderly widows' total needs, and the greater adult children's total needs, the more likely elderly widows were to co-reside rather than to live alone. As a result, the findings of this study supported environmental press theory and need contingent theory rather than a cultural preference explanation of co-residence rates.