This chapter examines the promotion of children’s positive mental health within the health promoting schools framework. The chapter provides an overview of implementation components critical to health promoting schools practice. Following this, research on the implementation of the Zippy’s Friends emotional wellbeing programme for primary school children is presented. This study is provided as an example of a multi-method evaluation approach, combining the use of a clustered randomised control design with qualitative approaches documenting the process of implementation, and case studies exploring the contextual factors that influence the process and outcomes. Key findings from this evaluation study are presented and the implications for researching the implementation of interventions within a health promoting schools approach are considered.