Despite a growing body of literature linking social activities to cognitive function, studies specifically examining the potential cognitive benefits of friendships and neighbors remain limited. Drawing on eight waves of nationally representative data from the Health and Retirement Study (1998–2012; N = 29,777), we investigated whether two distinct forms of social activities with friends and neighbors—(1) getting together for a social visit and (2) providing informal helping—were associated with cognitive function, which was assessed with a modified version of the Telephone Interview for Cognition Status (m-TICS). Multilevel models provided evidence of within-person associations between both types of social activities (with friends and neighbors) and better cognitive function, with informal helping showing more robust associations. This study highlights the value of an adequate level of contact with friends and neighbors, emphasizing the importance of accessible and meaningful social activities for older adults’ cognitive health.