While the factors that influence the well-being of individuals in late life have long been a major concern of research in aging, they have been a particularly active area of research and debate since the 1980s and continue to have a prominent role in gerontological research and debate. Early research on aging (from the 1920s to the 1960s) focused largely on examining typical problems that come with aging. The term successful aging was initially used to describe those who aged better than expected. In the 1980s, the MacArthur Network on Successful Aging, concerned that the field of gerontology had become preoccupied with disease and disability to the neglect of studies of the factors that fostered doing well in late life, conducted a series of studies of high-performing older persons and formulated the MacArthur theory of successful aging, which included three principal components: avoidance of disease, maintenance of physical and cognitive function, and engagement with society. Since its initial publication, the concept of successful aging has been applied to many subpopulations of older persons based on geography (East vs. West), socioeconomic status, race and ethnicity, religion, cognitive or physical function, and disease states.