Theatre-in-education for preventing illicit substance use among adolescents: protocol for a mixed-methods realist evaluation

Background: Illicit substance use remains a significant public health challenge among adolescents in the UK, with prevalence particularly high in areas of South East England. Early intervention is critical for preventing escalation and promoting resilience in young people. Theatre-in-Education offers a promising approach, combining professional theatre performance with structured educational activities to engage students both cognitively and emotionally. Despite its growing use in Personal, Social, Health and Economic education, robust evidence on its effectiveness and mechanisms of action for substance use prevention is limited. Methods: This protocol describes a mixed-methods realist-informed evaluation of a multi-component Theatre-in-Education intervention delivered in secondary schools across East Sussex. The intervention comprises a live theatre performance, lesson plans, a teacher training webinar, and classroom discussions. The evaluation adopts a realist approach to explore not only whether the intervention works, but also how, for whom, and in what contexts. Quantitative data will be collected via pre- and post-intervention questionnaires with pupils and school staff to assess changes in knowledge, refusal self-efficacy, wellbeing, and social influences. Qualitative data will be generated through audience observations, creative pupil focus groups, interviews with school staff, and parent/carer focus groups. Data will be analysed using realist-informed evaluation and triangulation approaches, with integration of findings to develop context–mechanism–outcome configurations. A health economics analysis will be conducted to assess costs and benefits, including value for money. Analysis will also be carried out to assess potential impact on health inequalities. Discussion: This evaluation aims to provide vital evidence on the effectiveness, execution, and equity of Theatre-in-Education as a strategy for preventing illicit substance use in adolescence. By examining both outcomes and underlying mechanisms, the study will inform future adaptation and scale-up of arts-based interventions in drug education and contribute to understanding how best to support young people’s health and wellbeing in diverse school contexts. The involvement of young people, school staff, and parents as active research partners ensures the study is responsive to real-world needs and settings. Trial registration: The study was registered with the ISRCTN registry (ISRCTN52466797) on 24/04/2025.