The 5th annual Mild Cognitive Impairment Symposium, held on April 13th and 14th, 2007, in Miami Beach, Florida, focused on the question of whether the time has come to revise criteria for Alzheimer disease (AD). The symposium, sponsored by the Wien Center for Alzheimer's Disease and Memory Disorders, Mt Sinai Medical Center in Miami Beach, Florida; and the Byrd Alzheimer Center and Research Institute in Tampa, Florida, brought together an international group of clinicians and researchers to examine current evidence for developing new criteria for AD and for outlining areas that still require clarification. Neuropathologic, neuroimaging, epidemiologic, and clinical perspectives were presented and discussed, as well as the impact of ethnic and cultural differences. As became evident, each perspective introduces different challenges in terms of selecting the appropriate assessment tools; determining when, where, and by whom the diagnosis should be given; and deciding whether multiple sets of criteria are needed for use in different settings, for example, research versus primary care practices. As was intended, the symposium delivered no consensus; however, there was substantial support for the idea that AD can and probably should be diagnosed before the onset of dementia, particularly as new interventions become available.