Introduction: The prevalence of co-occurrent substance use and psychiatric disorders is high. Contingency-based interventions have been shown to be effective in promoting adherence to treatment for people with substance use disorders but are among the least used evidence-based interventions for clients with comorbid psychiatric disorders, related to acceptability issues. Objective: The present implementation study aims to evaluate the acceptability and feasibility of a contingency approach in co-occurring disorders specialized treatment services. Methodology: Focus groups were conducted with health professionals and service users recruited from a specialized co-occurring disorder program (COD). Pre-intervention focus groups were conducted to select preferred modalities to implement the program. Post-intervention focus groups were conducted to document the satisfaction and benefits of the intervention. Throughout the study, program monitoring was conducted systematically to determine the gaps between planned and actual interventions. Results: Both health professionals consulted and service users agreed that the contingency approach could be integrated within usual co-occurring disorders treatment. In general, patients more readily accepted the contingency approach than health professionals. The higher functioning level group reported several benefits from the approach and implementation in its group sessions went as planned. Contingency approach was described by all participants as consistent with general treatment goals and led to patient’s awareness about their group attendance. Conclusion: This study highlights several challenges related to the implementation of a contingency approach. It also suggests that implementation of this approach could benefit from taking into account the needs and perspectives of service users.