The Daily Mile motivates children to be more physically active through proven theoretical pathways, such as promotion of autonomy (empowering children to set their pace and teachers to choose when and how to run the programme), engendering a sense of belonging (inclusive of all children, connecting with others and their teachers) and achieving competence (simple skill that is easily achieved and sufficiently challenging). However, the Daily Mile does potentially reduce classroom time by 75 minutes each week, thus displacing other activities, the value of which is unknown. Therefore, it is important for the programme to be rigorously assessed to evaluate whether the expected benefits are realised in practice, whether any effects are equitably distributed and that there are no adverse effects (such as physical activity-related teasing), all offset against the cost of the displaced activities.