This paper reports the findings of a qualitative study that explores the experiences of African-Caribbean, black African and white British men aged 18 to 35 years who report a dual diagnosis and are in contact with health and social care services in east London (UK). Dual diagnosis refers to service users with both identified mental health difficulties, for example schizophrenia, borderline personality disorders, bipolar disorders, and some problematic substance abuse issues, such as heroin, crack, marijuana, khat, prescription drugs or alcohol. We conducted semistructured in-depth interviews with nine male service users: two African-Caribbean men, four black Africans and three white British men. Statutory and nonstatutory services were involved in recruitment. The topic guide around which the interview was structured asked about social circumstances at the time of the interview, the services they had used and how the services worked to meet their needs, or if there were aspects that needed improving. The interviews were recorded, transcribed and subjected to the framework approach to qualitative data analysis. Findings showed that participants’ histories were generally characterised by frequent hospitalisation, separation from family, and education problems. Participants reported varying effectiveness of services; this variation reflected the degree to which services addressed social and cultural needs. We identified khat use to be common among African male participants, cannabis use to be common among African-Caribbean participants, and poly-drug abuse, including cannabis, to be common among the white British subjects. Service providers were not consistently addressing substance misuse. Mental health issues seemed to be addressed more thoroughly, and there was some evidence that cultural aspects of health and social care were considered and addressed. In conclusion, we propose that healthcare providers reconsider the cultural capability of their services to engage hard-to-reach ethnic groups, that they reconsider the effectiveness of interventions for substance misuse, and develop skills in a range of interventions that reflect the patterns of substances used by specific ethnic groups.