Applying the ADAPT-ITT Framework to Develop a Team-based Mental Health Support Model for Young Adults Transitioning from Homelessness to Housing.

Young adults experiencing homelessness (YAEH) face disproportionately high rates of mental health challenges and substantial barriers to professional mental health services, yet few interventions have been developed specifically to address their dual needs for housing stability and mental health support. This paper describes the iterative adaptation process used to develop Charge Up!, a team-based, phase-structured psychosocial intervention for YAEH transitioning from homelessness into supported housing programs, specifically Rapid Rehousing (RRH) and Transitional Housing to Rapid Rehousing (TH/RRH). Guided by the ADAPT-ITT framework, the study employed a modified, multi-cycle adaptation process drawing on two evidence-supported models - Critical Time Intervention (CTI) and Cornerstone - to develop an intervention tailored to the unique developmental, social, and structural needs of YAEH. The adaptation process engaged multiple stakeholders across sequential phases, including young adults with lived expertise through a Young Adult Working Group, housing and mental health professionals, and topical experts. Data were collected through focus groups, structured reflections, qualitative interviews following a feasibility pilot, and expert review of draft manuals, and were analyzed using inductive thematic analysis. Key findings across data sources affirmed the acceptability and feasibility of the intervention and identified cross-cutting themes including the need for a holistic, team-based model; non-traditional, stigma-reducing mental health support; the value of lived expertise through a peer provider role; employment as a central focus; and the importance of guiding values co-developed with young adults. Implications for intervention development, the ADAPT-ITT framework, and future testing are discussed.