A longitudinal study of a matched sample of 60 recently widowed and 60 married men and women tested predictions from stress and attachment theory regarding the role of social support in adjustment to bereavement. Stress theory predicts a buffering effect, attributing the impact of bereavement on well-being to stressful deficits caused by the loss and assuming that these deficits can be compensated through social support. In contrast, attachment theory denies that supportive friends can compensate the loss of an attachment figure and predicts main effects of marital status and social support. Attachment theory further suggests that marital status and social support influence well-being by different pathways, with the impact of marital status mediated by emotional loneliness and the impact of social support mediated by social loneliness. Results clearly supported attachment theory.