The hypothesis that the ability to comfortably spend and use time alone is a buffer against effects of stress, comparable to social support, was tested. A 20-item instrument was developed to evaluate the capacity to be alone (Winnicott, 1958) and was then administered by telephone survey to 500 U.S. adults. Findings differed for two dimensions of the capacity to be alone. Reported comfort in being alone was found to be related to lower depression, fewer physical symptoms, and greater satisfaction with life. Reported ability to use time alone to deal with stress was not related to well-being. Neither dimension showed the expected interaction with stress, and individuals with high stress who reported high solitary coping exhibited greater vulnerability on one dimension of well-being, suggesting that this coping style may reflect maladjustment.