Background: Depression creates a substantial personal burden for affected individuals and their families, and produces significant economic and social hardships that affect society as a whole. In Belgium, depression is a leading cause of disability, measured as disability-adjusted life years. The COVID-19 pandemic has greatly exacerbated the already substantial health and socioeconomic consequences of depression and has led to major changes in the need for and delivery of mental health services. Integrating mental health services into primary care is the most viable way to closing existing treatment gaps. The majority of people with mental disorders treated in primary care have good outcomes, particularly when linked to a network of services at secondary level and in the community. A balanced model of depression care calls for a system with community-based mental health care, delivered by primary care physicians and supported by other professionals in an eco-system of care. Aim: Implementation of an integrated depression care (IDECA) intervention in two regions in Flanders, Belgium with evaluation of the intervention’s working components, its acceptance by patients and care providers, and the contextual conditions which needs to be fulfilled to safeguard success of the model of care. Methods: A scientific steering committee including multiple academic expertise areas and patient representatives guided the development of the intervention and its scientific evaluation. Moreover, feedback was obtained from the Flemish Institute for Primary Care (VIVEL), the Family Doctors Medical Association (Domus Medica), and a mental health interest group(Psyche VZW). This resulted in an implementation design without control group and a targeted heterogeneous patient population with depression to obtain real-world evidence. IDECA consists of three intervention pillars: (i) the integration of two reference persons mental health (case management function) into general medical practice and who provide diagnostic support, ...