This randomised controlled trial specifically addresses the role of the CCC as change agents by implementing best-practice policies that are critical to intervention maintenance and an effective mediator of change. Our primary outcome of interest was change (e.g. improvement) in the CCC nutrition and physical activity environment to ultimately support healthy weight during these critical years of development. It was hypothesised that those CCC randomised to HC2 would show improvement in the nutrition and physical activity environment to support healthy weight among child attendees v. control centres. A secondary aim was to perform a separate analysis to explore a joint model that included the combined EPAO nutrition and physical activity subscores as one outcome. (author abstract)