The sociology of aging is both broad and deep. The breadth of the field can be highlighted in several ways. First, the sociology of aging encompasses investigations of aging as a process, of older adults as a group, and of old age as a distinctive stage of the life course. Second, aging research is performed at multiple levels of analysis, from macro-level studies of age structure within and across societies, to meso-level studies of labor-force participation and family structure, to micro-level investigations of health and well-being. Third, aging research uses the full repertoire of methods that characterize the discipline, including life tables and other demographic methods, survey research, ethnographic methods, and observational studies. The depth of the field results from the accumulation of scientific studies that now span more than three-quarters of a century.