New Zealand children's physical activity, including independent mobility and active travel to school, has declined markedly over recent decades. For adults, the design of our cities and neighbourhoods influences physical activity. This research investigates how neighbourhood-built environments influence the independent mobility, active transport, and physical activity of children aged 9 to 12 years. Child-specific indices of walkability, destination accessibility and traffic exposure will be constructed to measure the built environment in 12 neighbourhoods in Auckland. Interactive mapping software will be used to measure children's independent mobility and transport mode to destinations. Physical activity will be measured using 7-day pedometry. Body size will be objectively measured. Multi-level modelling approaches will be used to understand how the built environment impacts on children's physical activity and independent mobility. This is timely as cities throughout New Zealand develop and implement plans to improve the liveability and environmental resiliency of urban neighbourhoods. This grant was awarded to Auckland University of Technology but was later transfered to The University of Auckland.