Despite an increase in the provision of effective school-based interventions in recent times, there is an absence of literature for teachers focusing on the translation of promising interventions into real-world practice. The aim of this research was to provide a social-ecological guide for teachers of the external validity of implementing the Lunchtime Enjoyment Activity and Play (LEAP) school playground intervention. This research presents the process evaluation of a school playground intervention using RE-AIM (Reach, Effectiveness, Adoption, Implementation, Maintenance) as the theoretical evaluation framework. Data collection consisted of a mixed methods approach for two and a half years including a teacher focus group, direct observations and field notes. The process evaluation confirms the LEAP intervention as cost-effective, sustainable and transferable that is capable of enhancing multiple social-ecological factors within a school playground.