The role of the physician is critical in the evaluation of cognitively impaired patients for two reasons: (a) The longitudinal relationship between the patient and physician provides a unique opportunity to observe changes over time, generating confidence that may encourage the patient and family to report any concerns; (b) All research in this field is geared toward the earliest possible intervention, a process made possible by early diagnosis. Preparations for interview and the interview process itself require special knowledge of dementia on the part of the evaluating physician, who must understand the potentials and problems of both the content and the process of taking a history from the demented patient and his/her caregivers.