Physical activity is crucial for young children’s health and development. Many young children do not meet the recommended 3 hours of daily physical activity, including 60 min of energetic play. Early childhood education and care (ECEC/childcare) is a key setting to intervene to improve children’s physical activity. The Play Active programme is a scalable evidence-informed ECEC-specific physical activity policy intervention with implementation support strategies to improve educators’ physical activity-related practices.

This hybrid type III effectiveness-implementation trial will use a quasi-experimental repeated measures design to assess the real-world effectiveness of Play Active’s scalable implementation support strategies in helping ECEC services adopt the practices included in the Play Active policy. Secondary aims will examine changes in educator-reported and device-measured children’s physical activity; assess the sustainability of the programme; identify effective dissemination strategies; assess cost-effectiveness; and involve comprehensive process evaluation. All ECEC services in Western Australia (n=776), Queensland (n=1744) and South Australia (n=445) will be invited to participate. Data will be collected at baseline, 6, 12, 18, 24 and 30 months.

Ethics approval has been provided by The University of Western Australia Human Research Ethics Committee (HREC) (2023/ET000187), the University of Queensland HREC (2024/HE000076) and the University of South Australia HREC (206023). This real-world trial of Play Active is vital for understanding its implementation in practice and to generate evidence for further scale-up and roll-out nationally. Key findings will be disseminated to stakeholders, collaborators, policy-makers as well as families and practitioners in the ECEC sector.

ACTRN12624000406505.