Theories of aging have major implications for age differences in the self-concept across the adult lifespan that remain largely untested. Here, I propose a new perspective that draws from prominent aging theories to argue that people come to adopt a more interdependent self-construal with age as social environments become increasingly interdependent. Accordingly, I explain how ontogenetic development across the adult lifespan may emphasize interdependent social environments and subsequently encourage one to adopt a more interdependent self, explore how this perspective dovetails with prominent aging theories, and apply this perspective within the context of aging and prosocial behavior to support three studies (and one pilot study) within a Western cultural context to investigate the connection between aging, interdependence, and prosociality. In Study 1, I demonstrate within- and between-person age differences in the conduciveness of immediate social environments to the internalization of an interdependent self-construal. In Study 2, I replicate previous findings of an association between age and prosociality and interdependent self-construal and prosociality whilst demonstrating a positive relationship between age and interdependent self-construal. Lastly, in Studies 3a and 3b I validate and use a manipulation that makes participants experience some aspects of aging (using software that progresses the age of participants’ faces) and a novel manipulation of salience of interdependence to generate differences in interdependent self-construal, prosocial values, and actual prosocial behavior that are consistent with previously reported age differences in these constructs. Overall, these findings provide triangulating evidence across a variety of samples and methodologies to support a connection between aging, interdependence, and prosociality
