Health decision aids are a potentially valuable adjunct to patient-physician communication and decision making. Although the overarching goal of decision aids--to help patients make informed, preference-sensitive choices--is widely accepted, experts do not agree on the means to achieve this end. In this article, the authors critically examine the theoretical basis and appropriateness of 2 widely accepted criteria used to evaluate decision aids: values clarification and reduction of decisional conflict. First, they argue that although clarifying values is central to decision making under uncertainty, it is not clear that decision aids--as they have been conceived and operationalized so far--can and should be used to achieve this goal. The pursuit of clarifying values, particularly values clarification exercises, raises a number of ethical, methodological, and conceptual issues, and the authors suggest research questions that should be addressed before values clarification is routinely endorsed. Second, the authors argue that the goal of reducing decisional conflict is conceptually untenable and propose that it be eliminated as an objective of decision aids.