 The paper describes a participatory model development approach for mental health applications of systems modeling in eight different sites across Australia, which involves engaging with a range of participants, including people with lived experience of mental health issues, to define, refine, and validate the systems models. The process centers around three workshops where participants actively engage in group model building activities. The paper provides a detailed blueprint for the implementation of this process from 2022 to 2025, with site engagement commencing in August 2021 and the first modeling workshop scheduled to commence in February 2022. This article was authored by Louise Freebaron, Joanne Acapinti, Yenju C Song, and others.