Introduction The United Nations has issued a call to action for schools to deliver evidence-based prevention programs to address the growing burden of mental health, but implementation has failed in real-world settings. There is a need for implementation scientists to develop and trial strategies to address this translational problem.

Methods In this qualitative study, we used interviews with school staff (N=16) and performed a realist evaluation of a multicomponent implementation strategy called PAX Plus, designed to enhance the adoption of international evidence-based mental health prevention program, PAX Good Behaviour Game, in New South Wales primary schools.

Results The PAX Plus strategies consistently reported to improve implementation outcomes were having a recognition system for positive reinforcement, leadership support through monthly meetings, training and distributing support resources. Strategies that did not appear to work but could potentially be reformatted were monitoring progress using self-report methods, distributing e-newsletters with practical tips and having an online peer learning network.

Conclusion Internationally, school-based practitioners can use findings from this study to develop/adapt their own strategies to improve the implementation outcomes of mental health prevention programs which will improve effectiveness outcomes. Improving the effectiveness of mental health prevention programs is a priority to address Sustainable Development Goal 3.4, to reduce premature death from non-communicable diseases by one third by 2030.

Learning Outcomes We recommend school-based practitioners use recognition systems, training, leadership support and streamlined resources to increase the likelihood a mental health prevention program will be adopted and sustained in schools.