Physical function is a significant component of health-related quality of life among older adults. Potential correlates of healthy aging, including health behaviors and social network characteristics, were examined among 56,436 US women aged 55-72 in 1992. Healthy aging was assessed by maintenance of physical function measured by four subscales of the Medical Outcomes Study Short Form (SF)-36 Health Survey: physical functioning; role limitations; freedom from bodily pain; and vitality. Individual health behaviors, defined as current smoking, alcohol consumption, sedentary behavior, and being overweight each contributed to significant decrements in functioning across all age-groups. After controlling for these health behaviors and other confounders (age, race, education, and co-morbid conditions), elements of a woman's social network were significantly correlated with functional status. Strong predictors of high functioning among older women were having close friends and relatives and presence of a confidant. For example, the absence of a confidant was associated with a 4.44 point reduction in physical functioning (95% CI: -7.0, -1.9), and a 5.68 point reduction in vitality (95% CI: -7.9, -3.4). These effects were comparable in magnitude to those observed among heavy smokers, or women in the highest category of body mass index.