Objectives: Socialization predicts cognitive aging outcomes. Neighborhoods may facilitate socially engaged aging and thus shape cognition. We investigated places where older adults socialized and whether availability of these sites was associated with cognitive outcomes. Methods: Qualitative analysis of interviews and ethnography with 125 older adults (mean age 71 years) in Minneapolis identified where participants socialized outside of home. This informed quantitative analysis of a national sample of 21,151 older Americans (mean age at baseline 67 years) from the Reasons for Geographic and Racial Differences in Stroke study. Multilevel generalized additive models described associations between access to key social places and cognitive function and decline. Results: Qualitative analysis identified eateries, senior centers, and civic groups as key places to socialize. We identified significant positive associations between kernel density of senior centers, civic/social organizations, and cognitive function. Discussion: Specific neighborhood social infrastructures may support cognitive health among older adults aging in place.