Objective: Social activity is associated with healthy aging and preserved cognition. Such activity includes a confluence of social support and verbal interaction, each influencing cognition through rarely parsed, mechanistically distinct pathways. We created a novel verbal interaction measure for the Wisconsin Registry for Alzheimer’s Prevention (WRAP) and assessed reliability of resultant data, a first step toward mechanism-driven examination of social activity as a modifiable predictor of cognitive health. Method: Two WRAP subsamples completed a test–retest study to determine 8-week stability (n = 107) and 2-year stability (n = 136) of verbal interaction, and 2-year stability of perceived social support. Reliability was determined using quadratic-weighted kappa, percent agreement, or correlation coefficients. Results: Reliability was fair to almost perfect. The association between social support and interaction quantity decreased with age. Discussion: Social activity data demonstrate moderate to excellent temporal stability. Moreover, in older individuals, social support and verbal interaction represent two distinct dimensions of social activity.