Membership in important social groups can promote a positive identity. We propose and test an identity resource model in which personal self-esteem is boosted by membership in additional important social groups. Belonging to multiple important group memberships predicts personal self-esteem in children (Study 1a), older adults (Study 1b), and former residents of a homeless shelter (Study 1c). Study 2 shows that the effects of multiple important group memberships on personal self-esteem are not reducible to number of interpersonal ties. Studies 3a and 3b provide longitudinal evidence that multiple important group memberships predict personal self-esteem over time. Studies 4 and 5 show that collective self-esteem mediates this effect, suggesting that membership in multiple important groups boosts personal self-esteem because people take pride in, and derive meaning from, important group memberships. Discussion focuses on when and why important group memberships act as a social resource that fuels personal self-esteem.

There is growing evidence that social identity processes play an important role in a range of health outcomes. However, we know little about the nature and effectiveness of interventions that build social identification with the aim of promoting health. In the present research, we systematically review and meta-analyze interventions that build social identification to enhance health and wellbeing. A total of 27 intervention studies were identified (N=2,230).Using random-effects meta-regression, results indicate that social identification-building interventions had a moderate-to-strong impact on health (Hedges g=0.66; 95%CIs[0.34, 0.97]). Analyses revealed significant variation in intervention effectiveness as a function of its type: group-relevant decision making (g=1.26), therapy programs (g=1.03), shared activities (g=0.40), and reminiscence (g=-0.05). By contrast, there was much less variation across health outcomes: quality of life (g=0.81), physical health (g=0.77), self-esteem (g=0.69), well-being (g=0.67), (reduced) anxiety (g=0.61), (reduced) depression (g=0.58), cognitive health (g=0.55), and (reduced) stress (g=0.49). Finally, speaking to the mechanism of the interventions, results suggest that interventions tended to be more effective to the extent that they succeeded in building participants' social identification with the intervention group. We discuss the theoretical and practical implications of social identification-building interventions to foster health and outline an agenda for future research and practical application.

The homeless are a vulnerable population in many respects. Those experiencing homelessness not only experience personal and economic hardship they also frequently face discrimination and exclusion because of their housing status. Although past research has shown that identifying with multiple groups can buffer against the negative consequences of discrimination on well-being, it remains to be seen whether such strategies protect well-being of people who are homeless. We investigate this issue in a longitudinal study of 119 individuals who were homeless. The results showed that perceived group-based discrimination at T1 was associated with fewer group memberships, and lower subsequent well-being at T2. There was no relationship between personal discrimination at T1 on multiple group memberships at T2. The findings suggest that the experience of group-based discrimination may hinder connecting with groups in the broader social world — groups that could potentially protect the individual against the negative impact of homelessness and discrimination.

Maladaptive schemas are modifiable in short-term therapy or even in community settings. The experience of being accepted and belonging to a social group can challenge a person's deep-seated belief that they are socially isolated. Positive social experiences may act as scaffolding to help socially isolated individuals build new social group memberships. Less positively, social isolation schema can also act as a feedback loop, preventing people from identifying with groups, resulting in a negative social experience that may further embed the schema. Further research is needed to determine how clinicians might facilitate social identification.

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