Using Intervention Mapping to co-design a psychosocial service with youth experiencing mental illness

Background: Descriptions of service development processes in the youth mental health sector are lacking. Further, youth with lived experience of mental illness are rarely involved in service design. Intervention Mapping (IM) is a well-established framework for program development, implementation and evaluation, yet its applicability in the youth mental health sector is unknown. This paper describes the use of IM methodology to co-design and develop a psychosocial service to support youth aged 10–25 years experiencing mental illness in Tasmania, Australia. Methods: The six steps of IM were followed: 1) needs assessment; 2) define program outcomes and objectives; 3) program design; 4) program production; 5) implementation planning; and 6) evaluation planning. Results: Key outputs of each IM step are described. The service was successfully co-designed with young people at the centre of each step. The service includes wrap-around psychosocial support from lived-experience peer-support workers; outreach; and flexible frequency/intensity/duration to achieve young people's psychosocial goals. Conclusions: This is the first study to document the use of IM in co-designing a psychosocial service with youth experiencing mental illness. IM may provide a valuable roadmap for the youth mental health sector in supporting collaborative service design, implementation and evaluation planning, and systematic documentation of service development.