Developing programme theory for a place-based, systems change approach to adolescent mental health: A developmental realist evaluation.

Kailo is a prevention framework that supports local communities to co-design evidence-informed strategies to address the social determinants of adolescent mental health and wellbeing. Similar place-based initiatives exist internationally but research into the mechanisms of change and contextual drivers is limited. Understanding how and why Kailo functions is crucial for refining the framework before it is implemented in different contexts and for informing the focus of an impact evaluation. We conducted a developmental, realist-informed evaluation to investigate how and why the Kailo framework functions, for whom and under what circumstances. The first phase of the evaluation involved a rapid realist review, observations of key processes, key informant interviews, and document analysis. These methods informed the development of a series of initial programme theories. The second phase involved testing and refining these initial programme theories through further interviews and focus groups with key informants. A realist dialogic approach was used throughout, and our work was supported by two Young People's Advisory Groups who provided input on both the approach and theory generation. We generated a series of programme theories that shed light on the underlying mechanisms through which the Kailo framework works, the ways in which context acts as a catalyst for change, and the outcomes prioritised. These programme theories fall into six themes: 1) Alignment; 2) Time; 3) Credibility; 4) Accessible Spaces; 5) Building a Shared Understanding/Mission; and 6) Creating Hope that Change is Possible. Our study has informed the further development of the Kailo framework and lays the groundwork for a subsequent contributory impact evaluation to assess how Kailo contributes to system-level change and, ultimately, improvements in adolescent mental health and wellbeing. The programme theories generated also contribute to a wider understanding of how complex place-based approaches may function.