Traditionally, old age has been characterized as a progressive decline of health and social life. This book presents a more balanced research-based view of aging by considering older people as active agents that make decision and steer their actions to yield well-being. Considerations, concepts, theories, and research designs relevant for aging studies are discussed. Development of active aging research is followed by chapters addressing functional capacity, activities, and participation and their promotion. Old people have lived a long life, and for research of old age, the life course approach is especially pertinent. Finally, work—paid and unpaid—is explored as a form of active aging.