Abstract Positive experiences of groups (e.g., the extent to which groups are important and supportive) tend to be associated with better retirement adjustment outcomes. However, group experiences are not always positive, and we know little about their varied contribution to adjustment outcomes. We addressed this gap by exploring the nature of social group memberships – in terms of varying positive and negative experiences of groups – to better understand how social group memberships shape retirement adjustment, life satisfaction and mental health. A latent profile analysis (using data from 489 retirees and their membership of 1887 groups) identified four profiles of social group memberships: optimal (63%), slightly straining (13%), low‐supportive (18%) and ambivalent (6%). Subsequent regression analysis showed that these different profiles of group membership were differentially associated with retirement adjustment outcomes: belonging to more optimal groups was associated with better perceived adjustment, higher life satisfaction and better mental health, while belonging to slightly straining and ambivalent groups contributed to poorer adjustment, lower life satisfaction and greater depression. These findings have implications for theory and practice, not least because they advance our understanding of the diversity of people's group memberships and their contribution to retirement and health outcomes.