Co-developing the Child and Adolescent Mentally Healthy Classroom (CAMH Class) intervention for use in routine teaching in secondary schools.

Addressing the mental health needs of children and young people requires integrated and multidisciplinary action to reduce the risk of detrimental outcomes. Schools offer a unique environment for such provision. However, there is a critical need for school-based interventions that are feasible, co-designed, transdiagnostic, sustainable, and cost-effective beyond the conclusion of the trial, while aligning with pupil and teacher preferences. The current study reports the development phase of a new school-based transdiagnostic mental health intervention, embedded into routine classroom lessons, which aims to promote mental health and prevent the onset or escalation of mental health symptoms in young people. The study involved a total of 32 participants aged 15-63 years (Mage = 32.72, SD = 12.73), across three groups: one group of teachers (Mage = 36.80, SD = 11.29) took part in four sequential development workshops, one group of young people (Mage = 15.85, SD = 0.69) took part in one development workshop, and a new group of teachers who were not part of the initial development took part in one refinement workshop (Mage = 37.38, SD = 9.26). The study identified mental health priority areas in the classroom and brought together teachers and young people to co-develop activities that can be integrated directly into routine teaching to support and promote mental health. The intervention was deemed feasible and acceptable by both teachers and young people, subject to contextual considerations. Teachers perceived the activities to have a positive impact on young people's mental health, engagement, learning, energy, and overall enjoyment in class. The development of this intervention, with its co-production approach, has the potential to bridge the gap in intervention translation to the classroom and ultimately benefit young people's mental health.