The authors examined whether the effect of parental death on adults siblings' relationship quality varies on the basis of the presence and perceived effectiveness of a deceased parent's formal preparations for end-of-life care. The authors used data from the Wisconsin Longitudinal Study and focused on the relationship quality of a bereaved adult child and his or her randomly selected sibling. Parental death was associated with a decrease in sibling closeness. The parent's use of advance directives (living will and durable power of attorney for health care) did not have uniformly positive effects on adult siblings' relationship quality. Sibling relationships suffered when the living will was believed to "cause problems," but relationships improved when the deceased parent named someone other than his or her spouse or a child as durable power of attorney for health care. The authors discuss the implications for developing effective end-of-life preparations that benefit both the decedent and surviving kin.Keywords advance directives; bereavement; durable power of attorney for health care; living will; sibling relationships Parental death is a potentially distressing turning point for most adults because it severs one of the most enduring and emotionally significant bonds that individuals maintain over the life course (Moss and Moss 1983-1984). For midlife and older adults, the death of aged parents may force survivors to confront their own mortality and to critically reevaluate their lives and their role in their families (Umberson 2003). Deaths of elderly parents today typically occur after long-term illnesses that may require adult children to serve as caregivers (Marks et al. 2008) and to participate in difficult decisions about the prolongation or withholding of life-sustaining treatments. A vast body of research documents how relationships among midlife and older siblings are affected by their coordination of parental care during the final stages of their parents' lives (Checkovich and Stern 2002;Pillemer and Suitor 2006;Wolf, Freedman, and Soldo 1997). When adults perceive that they are providing more frequent or intensive parental care than their siblings are, relationships may grow strained both prior to and after the a parent's death (Hequembourg We know of no studies that explored whether adult sibling relationships following parental death are affected by parents' use of specific end-of-life health care preparations. Mounting research documents how aspects of end-of-life care, including the quality of medical care received by the dying patient (Carr 2003;Prigerson et al. 2003), the place of the death (Carr 2003), and the use of palliative care services (Miller, Gozalo, and Mor 2000) affect the psychological adjustment of bereaved older spouses. However, we know of no parallel studies exploring implications for bereaved adult children. We investigated one aspect of the end-of-life context: whether and to what end a deceased parent made formal preparations for end-of-life health care. Specificall...