Introduction

Retiring from work constitutes a major life transition that most people experience at some point in the course of their life, posing significant challenges to health and well-being. Indeed, large-scale longitudinal studies indicate that around 25% of retirees in the USA1 and around 10% of retirees in Germany2 experience a significant drop in health and well-being in the retirement transition. These figures point to the fact that retirement has significant costs for individuals and for society at large.

At the same time, however, such studies reveal significant variation in retirees’ experiences and health decline is not universal. Some retirees experience no change in health, and others actually experience improved health. This suggests that, beyond leaving one's job, there are a range of factors that determine whether retirees adjust well or poorly to this transition. In this regard, a growing literature points to the fact that social factors have a profound impact on people's health. For instance, meta-analytic evidence3 shows that people's social relationships with others is a significant predictor of their longevity and in fact a stronger predictor than other health behaviours such as physical exercise, smoking or alcohol consumption. Similarly, longitudinal evidence indicates that social engagement (or the lack of social isolation) is predictive of several key aspects of health,4–7 being associated with reduced depression8 and enhanced cognitive health.9 Clearly, social connectedness has significant implications for health. So, how and why might social connectedness be relevant for retirees?

In the present paper we argue that part of the variance in health and quality of life of retirees can be explained by the implications that retirement has for people's social group memberships—and their social identities or the sense of self that is derived from membership in one or more social groups.10–12 In more formal terms, we define a social group as a group of any form that a person is a member of and that he or she sees as an important part of their identity. For example, these groups can be leisure groups (eg, a book club), family, friendship or community groups (eg, a church group), sporting groups (eg, a tennis club), work groups (eg, a sales team), professional groups (eg, a trade union) or any other groups that a person sees as an important part of who they are. More specifically, we argue that retirement has an important bearing on health and quality of life because it typically involves relinquishing social group memberships (eg, as a member of a particular professional group, a particular organisation, a particular work-team) that have been a key focus for people's self-definition for years or decades. At the same time too, it can also provide opportunities to develop new group memberships, and hence for particular forms of socially engaged life. In line with previous work that has pointed to important links between group membership and health,13–15 our general argument is that the consequences of retirement for health and quality of life will depend in part on its implications for the constellation of group memberships that define an individual's sense of self.

The process of adjusting to retirement Retirement is conceptualised as a developmental process requiring adjustment that spans not only the transition from employment to retirement but also longer-term development post-retirement.16 Moreover, one's health and quality of life following the transition to retirement prove to be important indicators of successful retirement.17 However, there is significant variability in retirees’ health and quality of life, in part because the process of adjustment is shaped by an array of factors including the extent to which an individual participates in (1) financial planning and decision-making in the lead-up to leaving work,18–20 (2) bridge or volunteer work,21 ,22 (3) leisure activities23 ,24 and (4) physical activity.25 ,26 Moreover, and speaking to the aims of the present research, post-retirement adjustment is also dependent on a person's (5) ongoing social relationships that include family structures and wider social contacts.27 ,28 Such findings are also consistent with the literature showing that social factors have a significant influence on both psychological and general health.3–7 ,29–31

The role of social group memberships in adjustment to retirement Speaking to the importance of living a socially fulfilled life, an emerging body of research demonstrates the key role that social group memberships play in protecting health and well-being. People derive a sense of who they are from social groups (ie, their social identity), providing them with a sense of purpose, meaning, agency and belonging. Given their centrality to a person's sense of self, it is not surprising that when they are compromised this constitutes a major threat to psychological and social functioning.13 ,14 ,32 In line with this point, there is evidence that the number of groups that a person is a member of is a unique predictor of self-esteem,33 resilience34 and mental health.35–37 A growing body of research also supports claims that group-based interactions have a distinctive role to play in health and well-being over and above social interaction and social contact per se.15 ,38 ,39 Indeed, belonging to a greater number of social groups has been shown to be particularly protective of health when people undergo stressful life transitions such as becoming a university student,40 recovering from a stroke41 or coming to terms with a brain injury.42 Building on this body of research, we hypothesise that social group memberships will have an important role to play in adjustment to retirement. This is because transitioning to retirement is characterised by social losses associated with giving up work-related group memberships and associated identities.43 Speaking to this possibility, the present research is the first to examine the contribution that social group memberships—both old and new—make to post-retirement adjustment. In line with previous research, our core prediction is that once people have stopped work and are in the process of adapting to their new life circumstances, access to more group memberships will be a significant and unique predictor of successful adjustment. In this regard, the Social Identity Model of Identity Change (SIMIC)44 suggests that group memberships can offer protection against the stress-producing health consequences of life change. Moreover, it asserts that they do this in two ways; through (1) a continuity pathway involving the maintenance of old group memberships following the change and (2) a gain pathway involving the acquisition of new group memberships following the change. While continuity of group memberships following retirement and gaining new group memberships following retirement might be equally effective in protecting retirees’ health and quality of life, the maintenance pathway is likely to be less common among retirees. Whereas some may experience continuity of work-related identities through gradual transition to retirement, voluntary work or other means, this is not the case for everyone. Accordingly, for those who fully retire, the gain pathway of joining new groups following the transition might be particularly important because it can counter the experience of loss where work-related identities had been valued.