Living wills and other advance directives currently play a limited role in medical decision making. A new federal law, the Patient Self-Determination Act, will require health care providers in hospitals, nursing homes, and other facilities to inquire about the presence of advance directives, to record patient preferences in the medical record, and to develop institutional policies regarding the implementation of these directives. Unfortunately, the law does little to promote discussion or preparation of advance directives before hospitalization. Additional efforts to promote the use of advance directives can take place in the outpatient medical care system, in attorneys' offices, or through health insurers. Because most people have not yet prepared an advance directive, we suggest that institutions develop treatment policies for situations in which the wishes of patients who lack decisional capacity are not known. These policies should be designed to promote the patients' best interests, as defined by the consensus of the institutions' staff and members of the surrounding community.