biostudies-literatureUnknown65(1)Bachmann RSocial identity research has yet to fully engage with identity economics. This article bridges the two by examining capital market participation and capital income inequality - a critical economic behaviour and a societal issue that remain understudied in social psychology. We integrate psychological concepts and metrics of social identity with large-scale, representative UK data on household economics, encompassing 60,156 individuals and 130,598 observations from 2010 to 2023. Examining gender, ethnicity, education, occupation, politics, age and family as aspects of individuals' self-concept, our findings show that between- and within-person variations in these identities, beyond mere group memberships, were uniquely associated with both the presence and amount of capital income. Rather tThe British journal of social psychologye70025https://www.ebi.ac.uk/biostudies/studies/S-EPMC12673441biostudies-literatureSocial identity and capital income: A social psychological approach to identity economics using UK household data.PMC12673441Gleibs IHDelaney LBachmann RfalseSocial identity and capital income: A social psychological approach to identity economics using UK household data.Social identity research has yet to fully engage with identity economics. This article bridges the two by examining capital market participation and capital income inequality - a critical economic behaviour and a societal issue that remain understudied in social psychology. We integrate psychological concepts and metrics of social identity with large-scale, representative UK data on household economics, encompassing 60,156 individuals and 130,598 observations from 2010 to 2023. Examining gender, ethnicity, education, occupation, politics, age and family as aspects of individuals' self-concept, our findings show that between- and within-person variations in these identities, beyond mere group memberships, were uniquely associated with both the presence and amount of capital income. Rather t2026-01-01T00:00:00Z2026 Jan2026-06-05T22:18:43.848Z2026-05-22T03:15:43.833ZS-EPMC126734414133236010.1111/bjso.70025