The ways in which people age from birth to death over the life course depend upon where and when they live. Much evidence has been gathered to demonstrate that aging is not an immutable process; rather, aging varies as social structure varies and changes. But how does the life course vary? Under what conditions of place and time do particular individuals age in particular ways? This book, a companion to Aging from Birth to Death: Interdisciplinary Perspectives (edited by Matilda White Riley; AAAS Selected Symposium 30; Westview, 1979), addresses these questions from two perspectives. From the cross-cultural perspective, anthropologists and sociologists examine the cultural variability of aging as this variability reveals the nature and extent of social and cultural influences on the aging process, the lives of people of all ages, and the general significance of age norms and age-graded institutions in society. From the cross-temporal perspective, historians, sociologists, and demographers examine the impact of social change both on the process of growing up and growing old and on the place in society of people of all ages. The authors stress that the changing society is composed of people who are aging and who are not only shaped by, but are also continually shaping social institutions, values, and technologies. Thus, the book provides deeper understanding of the aging process, of the likely differences between the lives of past and future generations, and of the potential for optimizing these future lives.