This research investigates how urban neighbourhood environments can facilitate children's independent mobility (outdoor play and travelling to destinations unsupervised), thereby influencing physical activity accumulation and participation in daily life. The study will be located in six Auckland neighbourhoods, diverse in terms of urban design attributes which have the potential to influence children's mobility and physical activity. Participants will comprise 120 children aged 8-11 years and their parents/caregivers. Objective measures (global positioning systems, accelerometers, geographical information systems, observational audits) will be used to assess children's independent mobility and physical activity, neighbourhood infrastructure and streetscape attributes. Parents and children's neighbourhood perceptions and experiences will be assessed using qualitative research methods. This study will contribute children's experience and voice to urban planning to ensure children's health and wellbeing are to the fore in the transition to higher density neighbourhoods in Auckland and elsewhere in New Zealand.