Objective. To evaluate the impact of a multi-level intervention on the physical activity levels of 3-5 year old children attending center-based childcare services. Method. The trial was conducted in New South Wales Australia in 2010 in 20 centers with 459 children. The intervention, included: fundamental movement skill sessions; structured activities; staff role modelling; limiting small screen recreation and sedentary time; and anactivity promoting physical environment. Control services continued with usual routines. Physical activity during care was assessed using pedometers at baseline and at six months after baseline. Intervention implementation was assessed via observation of staff physical activity practices and audits of service environment and policy. Results. Mean step counts at baseline and follow-up were 17.20 (CI 15.94-18.46) and 16.12 (CI 14.86-17.30) in the intervention group and 13.78 (CI 12.76-14.80) and 13.87 (CI 12.57-15.17) in the control group (p=0.12). Intervention services showed significantly greater increases in the total minutes that teachers led structured activities, relative to control group services (p=0.02). Conclusion. The intervention showed no significant effect on child step counts per minute despite increasing time that staff delivered structured activity which is likely to be attributable to difficulties experienced by service staff in delivering a number of intervention components. (author abstract)