Researchers have increasingly turned their attention from younger individuals who hold age stereotypes to older individuals who are targeted by these stereotypes. The refocused research has shown that positive and negative age stereotypes held by older individuals can have beneficial and detrimental effects, respectively, on a variety of cognitive and physical outcomes. Drawing on these experimental and longitudinal studies, a theory of stereotype embodiment is presented here. It proposes that stereotypes are embodied when their assimilation from the surrounding culture leads to self-definitions that, in turn, influence functioning and health. The theory has four components: The stereotypes (a) become internalized across the life span, (b) can operate unconsciously, (c) gain salience from self-relevance, and (d) utilize multiple pathways. The central message of the theory, and the research supporting it, is that the aging process is, in part, a social construct.