Background Acculturation is a stressful process of adaptation to societal changes and may influence cultural identity (eg, choice of friendships, religiosity). Ethnic minority boys in the UK, however, have a mental advantage over their White peers. Examining the relationship between cultural identity, ethnicity and psychological well-being may reveal mechanisms for protecting adolescent mental health.

Aim To examine the impact of cultural identity on psychological well-being in an ethnically diverse sample of adolescents.

Method Longitudinal data on psychological well-being (Goodman's Strengths and Difficulties Questionnaire), cultural identity (ethnicity of friendships, racism, migrant status) and potential correlates (eg, socio-economic circumstances) were collected on 4785 adolescents, 80% ethnic minorities, in 51 schools in London, UK. Ethnicity of friendships was used to classify pupils as integrated (many friends of own/other ethnicity), traditional (mostly friends of own ethnicity), assimilated (mostly friends of other ethnicity) and marginalised (few friends). Linear mixed models explored the impact of cultural identity on psychological well-being between 12 and 16 y, and differential effects by ethnicity.

Results Psychological well-being improved through adolescence. Cultural identity was independently associated with psychological well-being among boys, with psychological well-being being most favourable in the integrated group and least so in the marginalised group. This effect did not vary by ethnicity or age and ethnic minority boys maintained a psychological well-being advantage over their White peers. Similar non-significant patterns were observed for girls.

Conclusion Acculturative processes impact on the psychological well-being of adolescent boys, regardless of ethnicity, and raises questions of how best to manage diversity in schools.