Although it is widely accepted that bereavement can result in health problems, little is still known about the factors that determine the impact of the loss on those left behind. The Leiden Bereavement Study attempted to address this problem, by examining the consequences of bereavement after suicide (N = 91), traffic accident (N = 93), and illness (N = 125) for first-degree family members. Seventy-three bereaved spouses, 68 parents, 86 siblings, and 82 adults who had lost a parent were interviewed in a longitudinal time-sample study. Multiple measures of physical, psychological, and social functioning, as well as details about the relationship and pre- and post-loss events, were obtained through in-depth structured interviews at 4 and 14 months after the loss. The results indicate that the influence of mode of death is small to absent for most aspects of psychosocial health. Post-traumatic stress symptoms were almost as common among the illness-bereaved group as they were among the unnatural death groups. The kinship relationship to the deceased played a prominent role in virtually all aspects of functioning, with parents (particularly mothers), widowers, and sisters of the deceased being more strongly affected than adult children, brothers, and widows. The characteristics of the relationship played a further important role in the level of problems after the loss. Early adaptation was highly predictive of longer-term adaptation. The implications of the findings for prevention and intervention are discussed.