A retrospective qualitative evaluation of barriers and facilitators to the implementation of a school-based running programme ChalkleyAnna RoutenAsh HarrisJo CaleLorraine GorelyTrish SherarLauren 2018 Background There is growing interest in school-based interventions which deliver opportunities for additional physical activity time outside of physical education (PE). A practical and cost-effective approach may be school running programmes. Consequently, many school-based running initiatives are currently being implemented in a grass-roots style movement across the UK. However, research on the implementation of physical activity programmes in schools is notably underdeveloped. Therefore, this qualitative study aimed to better understand the barriers and facilitators to the implementation of a running programme, Marathon Kids (MK), within primary schools in England. Methods Two sets of semi-structured interviews were conducted, the first with each of the three core members of staff responsible for MK, and the second with each of the MK school staff Champions from 20 primary schools. Also, nine focus groups were conducted with 55 pupils (6–10 years) from five of the schools; all were analysed using thematic analysis. Results Three themes were identified surrounding the barriers and facilitators to implementation: features of the programme (e.g. ethos and resources), school climate (e.g. culture; whole school engagement; PE and physical activity policies and goals; and physical environment) and programme implementation decisions (e.g. aspirations and planning and sustainability). Conclusion Findings suggest that the barriers and facilitators to implementation are wide-ranging and include programme, organisational and system-level factors. Collectively pointing towards the need for a preparation period before implementation to understand schools’ readiness to implement and context-specific factors, both regarding organisational capacity and programme specific capacity.