Daily social interactions provide access to key social resources, yet little research has examined how these interactions vary across geographic spaceâparticularly in later life. Using ecological momentary assessment data from a state-representative study of older adults in Indiana, we examine how interactions with different partners vary across a continuum of municipality population density. Further, we assess whether this variation is shaped by social opportunity structuresâsuch as number of community parks, theaters, and volunteer organizationsâand whether patterns persist during leisure time, when individuals are free to choose their interaction partners. Results show that higher population density is associated with more time spent alone, more interactions with âshared-foci partnersâ (i.e., partners known through foci of activity, such as neighbors, professionals, congregation membersâthough associations are driven primarily by professionals, strangers, and âothersâ), and fewer interactions with kin. Adjusting for social opportunity structures does not affect the observed association between population density and aloneness, interactions with shared-foci partners, or interactions with kin, indicating that differential access to social opportunity spaces does not explain these relationships. Restricting analyses to leisure activities reveals that differences in shared-foci partner interactions by population density disappearâimplying they are driven by variation in obligatory tasksâwhile differences in kin interactions and, to a lesser extent, time spent alone persist. By identifying population density as a structural factor that shapes everyday sociality, this study underscores the role of geographic context in structuring older adultsâ access to social connection and the resources embedded in daily interaction.