STATEMENT OF THE PROBLEM: Despite the huge burden of mental health problems, about 85% of people with severe mental illness in sub-Saharan Africa (SSA) do not receive any form of treatment. Integrating mental health services into primary health care (PHC) has been advocated as the most viable means of closing this treatment gap. The linear model of intervention development, efficacy testing and implementation led to problems with sustainability over time and in real world setting. As there are policy and ethical implications of developing effective heath programmes without sustainability and scale-up, an understanding of the factors and processes that influences sustainability and scale up of an evidence-based intervention is needed for proactive planning OVERALL AIM: This feasibility study aims to identify the strategies to facilitate the health system changes necessary to sustain and scale up mental health services in primary care in Lagos, Nigeria. SPECIFIC QUESTIONS TO BE ADRESSED BY THE PROJECT 1) what is the state of implementation of the MeHPriC Project and what are the factors that are currently underlying its implementation?; 2) What are the dynamic interactions between the different components of the programme as regards contexts (inner and outer), implementation processes, implementation actors and intervention outputs and outcomes?; 3) How do these components influence the sustainability of the programme; and 4) What strategies may be required to facilitate the changes necessary for sustainability and scale-up METHODOLOGY There are 5 phases of the study. 1. In Phase 1, We will review policy documents and conduct in-depth interviews with selected policy makers to develop hypotheses, assess whether the target indicators for the project are met, identify how they are met, identify the key contextual facilitators and constraints and the way they affect the outcome. 2. In Phase 2, we will conduct a quantitative survey amongst the stakeholders including policy makers and administrators, programme managers, PHC health workers and recipients of care. They will complete scales to assess organisational readiness to change, sustainability and perceived intervention acceptability and feasibility 3. In Phase 3, we will conduct a brief evaluation of the implementation and through in-depth interviews, we will examine the stakeholders' perception about the health systems constraints to delivering, scaling up and sustaining the intervention. We will also observe selected PHC facilities to enable us to understand the factors that act as facilitators or barriers to sustenance of the intervention delivery. 4. In Phase 4, we will conduct a Theory of Change (ToC) workshop that will draw mainly on the results from the analysis of the earlier phases in combination with scientific knowledge and programme experience to identify health system changes that will improve sustainability in the delivery of the intervention. 5. In Phase 5, we will analysis and present the project report to the funders and the stakeholders RESEARCH IMPACT: 1. The individual care recipients will benefit from sustained level of evidence-based interventions leading to better outcomes and improved quality of life. 2. This study will enhance the health workers knowledge, motivation and attitude in providing effective mental health interventions in a sustainable way. 3. The programme implementers will be able to identify and include sustainability components to their design and implementation of complex interventions. 4. Evidence generated in this study will be shared with the WHO team to inform potential strategies for a sustainability and scalability of mental health interventions in LMICs. 5. The project will inform Policy makers on methods of sustaining beneficial interventions thereby maximizing the judicious use of funds