ABSTRACT This small-scale study compares stakeholders’ perspectives regarding what makes a successful whole-school Mental Health Intervention. Four study groups were included from an all-ability coeducational secondary school in south-east England: Students (n = 8), Teachers (n = 5), School-Leaders (n = 3), and YMCA Youth Workers (n = 3). Students took part in a focus group whereas the adult groups participated in semi-structured interviews. Subsequently, all participants ranked potential aspects of what might make a successful whole school Mental Health Intervention. No theme was mentioned consistently across the four groups, suggesting a diversity of perspectives regarding the benefits of Mental Health Interventions. All participants, except teachers, valued student involvement, a feature confirmed by the literature. Teachers occasionally adopted misinformed perspectives – arguably a result of insufficient training. Generally, participants’ job roles informed their responses. However, a loose trend existed whereby School-Leaders’ results were more aligned to an external charity association – the Young Men’s Christian Association (YMCA) – than Teachers’ despite the fact that the Teachers and School Leaders worked in the same context. Although the single context and small sample sizes for this research compromise generalisability, there are clear recommendations to inform future studies and for those who are leading and providing whole-school Mental Health Interventions. This study is set within the political and policy contexts of a competitive, market drive English education system and can comment on the wider system within which this intervention nests.