Behavior genetic investigations of cognitive aging began in earnest in the 1980s. After an initial focus on general cognitive ability (GCA) in earlier lifespan periods, aging researchers turned their focus to investigations of age changes in GCA as well as specific cognitive abilities, finding different patterns of change with age and different compositions of genetic and environmental contributions to change. Mapping the human genome in the early 2000s provided researchers with tools to investigate multiple genes associated with cognitive function. Moreover, contexts in which cognitive aging occurs, as well as the role of gene and environment interplay, have become a focus.