Background: In traditional dual diagnosis treatment, the primary aim is to attend the substance use problem and tackle the mental health issues with little attention to the positive aspects of clients' lives. This deficit-based approach, however, may bring about an ignorance of clients' potentials. The present study primarily aimed at investigating practitioners' views of their clients; acquiring information on how to improve a previously designed positive psychology intervention for dual diagnosis, and finding ways of integrating positive psychology with current approaches. Methods: A positive psychology intervention developed for dual diagnosis individuals was delivered to two groups of psychosocial intervention workers (n = 17) at a drug and alcohol service. The study employed a mixed methods approach with a quantitative and a qualitative element (focus group). Results: Participants reported a number of personal and professional benefits gained from the intervention, but also discussed the structure of the intervention, practitioner qualities, and difficulties of incorporation into existing treatment as challenges that may arise in terms of feasibility with this client group. Conclusions: Through a strengths-based positive approach, a more balanced treatment would enable the recognition and appreciation of both the vulnerabilities and the emerging potential of clients. This would lead to better outcomes with clients achieved by a healthier workforce.