This study examines the relationships that exist between social isolation, support, and capital and nutritional risk in older black and white women and men. The paper reports on 1000 community-dwelling older adults aged 65 and older enrolled in the University of Alabama at Birmingham (UAB) Study of Aging, a longitudinal observational study of mobility among older black and white participants in the USA. Black women were at greatest nutritional risk; and black women and men were the groups most likely to be socially isolated and to possess the least amounts of social support and social capital. For all ethnic-gender groups, greater restriction in independent life-space (an indicator of social isolation) was associated with increased nutritional risk. For black women and white men, not having adequate transportation (also an indicator of social isolation) was associated with increased nutritional risk. Additionally, for black and white women and white men, lower income was associated with increased nutritional risk. For white women only, the perception of a low level of social support was associated with increased nutritional risk. For black men, not being married (an indicator of social support) and not attending religious services regularly, restricting activities for fear of being attacked, and perceived discrimination (indicators of social capital) were associated with increased nutritional risk. Black females had the greatest risk of poor nutritional health, however more indicators of social isolation, support, and capital were associated with nutritional risk for black men. Additionally, the indicators of social support and capital adversely affecting nutritional risk for black men differed from those associated with nutritional risk in other ethnic-gender groups. This research has implications for nutritional policies directed towards older adults. © 2004 Elsevier Ltd. All rights reserved.