Jetten, JolandaBranscombe, Nyla R.Haslam, S. AlexanderHaslam, CatherineCruwys, TeganJones, Janelle M.Cui, LijuanDingle, GenevieveLiu, JamesMurphy, SeanThai, AnhWalter, ZoeZhang, Airong2015-06-152015-06-152015-05-27Jetten J, Branscombe NR, Haslam SA, Haslam C, Cruwys T, Jones JM, et al. (2015) Having a Lot of a Good Thing: Multiple Important Group Memberships as a Source of Self-Esteem. PLoS ONE 10(5): e0124609. http://dx.doi.org/10.1371/journal.pone.0124609https://hdl.handle.net/1808/18063Membership 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.© 2015 Jetten et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are creditedhttp://creativecommons.org/licenses/by/4.0/SchoolsChildrenElderlyInterpersonal relationshipsQuestionnairesSocial networksSocial researchSocial theoryArticle10.1371/journal.pone.0124609openAccess