This study explores social workers' experience in working with clients who have co-occurring conditions, specifically ADHD and substance abuse and in particular narcotic-related misuse. The aim of the study is to explore how social workers describe their work with substance abuse investigations involving clients with ADHD, the obstacles they encounter, and whether they regard their knowledge and competence as sufficient during such cases. This study is based on a qualitative method adopting semistructured interviews with seven professionals with field experience with this group of clients. Two theories are used to interpret the empirical material, Street-level bureaucracy and power. The findings indicate that professionals perceive such cases as difficult and demanding. The reason being that clients’ use narcotics as a form of self-medication related to difficulties with emotional regulation, structure and everyday functioning. The results also show that professionals aim to alter their approach depending on the client in question. On the contrary, professionals also mentioned other limitations, being lack of specialized knowledge, organisational constraints that restrict their flexibility. Furthermore, insufficient collaboration between social services, psychiatry and addiction center is also described as an obstacle. Overall, this study highlights the need for increased knowledge, greater flexibility and improved interagency collaboration in order to provide more appropriate support for clients with co-occurring ADHD and substance misuse. encounter, and whether they regard their knowledge and competence as sufficient during such cases. This study is based on a qualitative method adopting semistructured interviews with seven professionals with field experience with this group of clients. Two theories are used to interpret the empirical material, Street-level bureaucracy and power. The findings indicate that professionals perceive such cases as difficult and demanding. The reason being that clients’ use narcotics as a form of self-medication related to difficulties with emotional regulation, structure and everyday functioning. The results also show that professionals aim to alter their approach depending on the client in question. On the contrary, professionals also mentioned other limitations, being lack of specialized knowledge, organisational constraints that restrict their flexibility. Furthermore, insufficient collaboration between social services, psychiatry and addiction center is also described as an obstacle. Overall, this study highlights the need for increased knowledge, greater flexibility and improved interagency collaboration in order to provide more appropriate support for clients with co-occurring ADHD and substance misuse.