The goal of the current project was to examine whether engaging in social activity may moderate or mediate the relation between age and cognitive functioning. A large age range sample of adults performed a variety of cognitive tests and completed a social activities questionnaire. Results did not support the moderator hypothesis, as age differences in cognition were similar in people who reported low and high levels of engagement in social activity. However, the data was consistent with a mediation model, which posits that age differences in social activity partly explain age differences in cognition. Furthermore, it supported a moderated mediation model, which assumes that the mediation effects of social activity were stronger at older ages. (Contains 3 tables and 3 figures.)