Background: Childcare centres are important environments for promoting physical activity and healthy eating. Blended approaches to professional learning may help overcome existing challenges for educators in promoting these behaviours. This study aimed to test the effect of a blended professional learning program on healthy eating and physical activity in childcare. Methods: Cluster randomized stepped-wedge trial in 15 childcare centres in Tasmania, Australia. Children aged 2-5y who attended at least two days per week were eligible to participate. Random assignment occurred at the centre level. Centre names were drawn out of a hat and then subsequently allocated to one of the three steps. The intervention comprised a 12-week blended professional learning program for educators. The main outcome was centre-level physical activity and healthy eating, assessed using the Environment and Policy Assessment Observation System (EPAO). All data collectors were blinded to step allocation. Analyse