OBJECTIVES: Students from lower socio-economic circumstances remain under-represented in UK medical schools despite recent shifts in other demographic variables and specific policy emphasis on widening participation (WP). This study aimed to further understanding of the reasons for this. METHODS: Volunteer participants at three English medical schools took part in narrative-style, in-depth interviews examining their pathways into medicine and the relationships between these pathways and participants' socio-cultural, educational and family backgrounds. This analysis uses findings from interviews with 12 mature students from working-class backgrounds. It employs theoretical work from the wider field of education sociology that has investigated the relationship between higher education decision making and class. RESULTS: This study demonstrates how 'normal working-class biographies', constructed by the majority of students targeted by WP activity, result from the influences of socio-cultural context, as well as familial and institutional habitus. The resultant influence on habitus as identity and, in particular, the disjuncture between working-class perceptions of medicine and individual identities are key to understanding the reasons behind the low number of working-class applicants to medical school. CONCLUSIONS: Interventions that aim to increase participation rates in medicine must address this disjuncture. This might be achieved by re-orienting working-class identities and perceptions of medicine as a profession. However, it should be acknowledged that 'identity conflict' is related to the elite image that medicine maintains within contemporary society and, as such, efforts to re-orient individual working-class identities may have only a limited impact on overall participation rates.