A realist inspired barriers and facilitators evaluation of the co-creation process in the Youth-centred Participatory Action Project.

This study examined barriers and facilitators of the first phase of the co-creation process as part of the Youth-centred Participatory Action (YoPA) project, a multi-country co-creation initiative to address health inequities by engaging adolescents in Denmark, Nigeria, South Africa, and the Netherlands. Using a qualitative design informed by implementation science and realist thinking, we analysed data from 22 transcripts of semi-structured interviews with researchers, facilitators, and external stakeholders, alongside 61 logbooks from co-creation sessions. Data were coded deductively using the PROSECO process-evaluation framework, followed by the development of exploratory Context-Mechanism-Outcome configurations. Findings highlight four predominant areas shaping the co-creation process: group dynamics, partnerships, contextual influences, and resources and support. Facilitators included psychologically safe spaces, horizontal communication, consistent facilitation, strong institutional partnerships, motivation driven by purpose and belonging, and access to organizational resources and staff support. Barriers were associated with socioeconomic adversity, unstable infrastructures, logistical constraints, competing priorities, uneven engagement, and challenges in translating complex systems-thinking concepts into youth-friendly practice. Realist interpretations suggest that when structured participation, trust, and relational support were present, they activated mechanisms of ownership, agency, and sustained engagement; conversely, low-resource contexts and activities overload hindered participation, feasibility, and engagement. This study contributes empirical evidence on co-creation processes with adolescents across diverse settings. It demonstrates the combined value of the PROSECO framework and realist-inspired analysis for evaluation and understanding of how context and mechanisms shape co-creation in health-related research. Implications include the need for resourcing relational work, and designing context-sensitive strategies when conducting co-creation with adolescents.