BACKGROUND: Whole-school interventions modify the school environment to promote health. A subset of these interventions promotes student commitment to school to prevent substance (tobacco, alcohol, other drugs) use and/or violence. A previous review identified the theory of human functioning and school organisation as a comprehensive theory of such interventions, and found evidence that these interventions reduce substance use and/or violence.

OBJECTIVES: The objectives were to search for, appraise and synthesise evidence to address the following questions: (1) What whole-school interventions promoting student commitment to school to prevent substance use and/or violence have been evaluated, what intervention subtypes are apparent and how closely do these align with the theory of human functioning and school organisation? (2) What factors relating to setting, population and intervention affect implementation? (3) What are the effects on student substance use, violence and educational attainment? (4) What is the cost-effectiveness of such interventions? (5) Are intervention effects mediated by student commitment to school or moderated by setting or population?

DATA SOURCES: A total of 56 information sources were searched (in January 2020), then an updated search of 48 of these was carried out (in May 2021). Reference lists were also searched and experts were contacted.

REVIEW METHODS: Eligible studies were process/outcome evaluations of whole-school interventions to reduce student violence or substance use among students aged 5-18 years attending schools, via actions aligning with the theory of human functioning and school organisation: modifying teaching to increase engagement, enhancing student-staff relationships, revising school policies, encouraging volunteering or increasing parental involvement. Data extraction and quality assessments used existing tools. Theory and process reports were synthesised qualitatively. Outcome and economic data were synthesised narratively; outcome data were meta-analysed.

RESULTS: Searches retrieved 63 eligible reports on 27 studies of 22 interventions. We identified four intervention subtypes focused on student participation in school-wide decisions, improving staff-student relationships, increasing engagement in learning and involving parents. The theories of change of most intervention subtypes aligned closely with the theory of human functioning and school organisation, and informed refinement of an intervention theory of change. Theories of change for interventions increasing learning engagement did not align with this theory, aiming instead to increase school commitment primarily via social skills curricula. Factors influencing the implementation included whether or not interventions were tailorable, workable and well explained. Interventions with action groups comprising staff/students, etc. and providing local data were well implemented. Implementation was also affected by whether or not schools accepted the need for change and staff had the resources for delivery. Meta-analyses suggest small, but significant, intervention effects in preventing violence victimisation and perpetration, and substance use. There was sparse and inconsistent evidence of moderation and some evidence of mediation by student commitment to school. Two economic evaluations suggested that there is the potential for the interventions to be cost-effective.

LIMITATIONS: The quality of the studies was variable and the economic synthesis was limited to two studies.

CONCLUSIONS: Whole-school interventions aiming to promote student commitment to school share similar theories of change and factors affecting implementation. They have the potential to contribute to preventing violence and substance use among young people. Future trials should aim to optimise intervention effectiveness by better theorisation, and assess implementation and effect moderators and mediators.