Individuals who maintain group memberships in their community tend to experience improved well-being relative to those who participate in few or no groups. There are, however, few investigations targeting variability in the correlates of group membership across the lifespan. The present examination probed age-related variability in the association between group memberships and subjective connectedness as well as well-being. Participants included 3,940 (mean age = 45.61 years, standard deviation [SD] = 15.62) Canadian and American respondents who completed an online survey during August of 2020 (i.e., amidst the COVID-19 pandemic). Time-varying effects modelling was used to estimate coefficients for group membership at each age within the sample. Memberships in social groups positively predicted connectedness, and this association was strongest in middle-to-older age; a similar association was also evident when predicting well-being. Connectedness was also a positive predictor of well-being throughout most ages. These findings build on emerging research conveying how group memberships have significance for people currently in middle-to-older age.