Aim: Addiction is considered a chronic disease associated with a high rate of unintentional relapses. Most of the current treatments focuses on relapse prevention or avoidance and control of its determinants. However, since only a small portion of concerned individuals access treatment, to find a way to offer support for safer consumption behaviors is of interest. The Harm Reduction (HR) approach and mental health recovery perspective offers another way to support individuals with alcohol addiction. The Vitae study is a realist evaluation of the impact, viability and transferability of the IACA! Program, a Harm Reduction program tailored to people with alcohol use disorders. Methods (Optional): The Vitae study adheres to the theorydriven evaluation framework where the realist evaluation method and contribution analysis are used to explore the effects, mechanisms, and influence of context on the outcomes and to develop and adjust an intervention theory. This study is a 12-month, multi-case, longitudinal descriptive pilot study using mixed methods. It is multicentered and carried out in 10 addiction treatment or prevention centers in France. The target number of participants with alcohol addiction (beneficiaries) was 100 and 23 health professionals. Qualitative analysis permit to assess viability and transferability conditions based on interview with professionals and beneficiaries. Descriptive analysis of quantitative variables will permit to assess alcohol use severity with the Addiction Severity Index (ASI), craving assessment and the Mini International Neuropsychiatric Interview (MINI) for comorbidities every 3 months, during 12-months. Conclusions: Viability and transferability of complex health interventions is a major public health topic and remains a highly valuable research field. This study, focusing on an innovative intervention for people with alcohol use disorder implemented in very different contexts will provide valuable information for the implementation science but also for the Harm Reduction field. Financial Support: INCa and IReSP< Réduire