For the past 50 years, the doctrine of informed consent has been the cornerstone of the protection of human subjects involved in research. Yet, when one considers research on dementia, such as Alzheimer disease (AD), one is immediately confronted by the dilemma of an illness that gradually impairs the capacity of potential research subjects to give informed consent. The methods suggested by ethicists for successfully addressing this dilemma include: 1) obtaining information directly from people with dementia, informed consent if they retain decisional capacity, and at least assent and preferences and values in the absence of the capacity to give informed consent; 2) obtaining advance consent, using advance directives for research modeled after the living will and durable power of attorney for health care employed in clinical decision making; and 3) a richer notion of the family as the unit of decision making, especially considering the role that families play in the lives of people with dementia. The central aim of this project is to empirically study whether these proposed methods for facilitating ethical research on subjects with dementia are feasible and effective. By combining the perspectives of several disciplines, and by using research vignettes and analysis of videotaped consent encounters, this project will answer practical questions about: the ability of dementia subjects to participate in research decision making despite their impairments; the utility of a multidisciplinary approach to yield a deeper understanding of informed consent and proxy consent for dementia research;' and the effectiveness of an advance consent process involving dementia subject and proxy together.