Book excerpt: Professionals working in addiction care in both Belgium and other European countries have identied a discrepancy between the prevalence of problem substance use among people with a migration background, and the presence of people with a migration background in treatment facilities. However, little research is currently available on this topic. This study attempts to ll the knowledge gap in existing research by exploring the patterns of substance use, expectations and treatment needs of people with a migration background in four Belgian target groups (the Turkish community in Ghent; the Eastern European communities in Ghent; the Congolese community in Brussels; and asylum applicants, refugees and undocumented migrants). Substance users with a migration background can be particularly dicult for researchers to reach, so community researchers were recruited to interview substance users from within their own network. Over 200 people were interviewed. The project was carried out in close collaboration with the respective communities and with stakeholders in addiction care. This book presents the ndings of the study, together with recommendations for health care policy and the practice of addiction care. It also details the explorative and qualitative community-based participatory research design (CBPR) that was used to facilitate the study.