As the number of elderly people in human populations increases, the study of normal aging, age-related disorders, and enhanced longevity is taking on new urgency. Fundamental research will provide means of preventing and effectively treating the most debilitating and distressing aspects of advanced age. Considerations of aging in non-human life forms do not aim at life extension, but at an increasing appreciation for the biological role of the aging process in populations, in addition to developing a more comprehensive understanding of the mechanisms of aging. The present volume focuses on primate aging because human characteristics that evolved during their evolution are homologous with those of other primates. Therefore, the research on nonhuman primates will decidedly also contribute to our understanding of the process of human aging. The topics of this volume include brain aging and neurodegenerative diseases, social behavior, cognition and aging, skeletal aging in natural and captive conditions, and consequences of caloric restriction for life and health extension. The great variety of contributions aim at providing a survey of the relevant work in progress and increasing the understanding of normal and pathological aging and life-span enhancement in a variety of nonhuman primate species.