The negative health outcomes of the rapid growth of children's sedentary culture are clearly expressed in the public health literature. They challenge professionals, public officials, and policy makers responsible for children's healthy development to create outdoor environments that motivate children and their carers to spend sufficient time outdoors engaged in physical play. Reliable evidence is required to guide the design and management of outdoor environments inhabited by different age groups. However, children who spend time outdoors need protection from the potentially harmful effects of solar radiation. The symposium presents research findings from four studies at different scales of childhood habitat: child development centres, urban parks, and urban neighbourhoods, aimed at building the evidence base for effective design of children's outdoor environments. Cosco presents research to identify discriminatory items for a pilot tool to rate the potential of preschool outdoor play setting attributes to produce higher levels of physical activity when three-to-five-year-old children are exposed to them. Mårtensson and Boldemann apply Outdoor Play Environment Categories (OPEC) and the Sky View Factor (SVF) as tools for environmental assessment of outdoor surroundings of schools and other institutional settings. The aim is to describe how the environmental parameters defined by the tools are related to physical activity and sun-preventive behaviour during outdoor play. Moore's study is focussed on how use of urban parks by children and families can be explained by the attributes of the park and neighbourhood’s social and physical form variables. Islam's study explain how older children's physical activity is influenced by neighbourhood characteristics in an Asian megacity. The studies employ behavior-environment methodologies. Independent variables are measured with environmental mapping, GIS coding, solar radiation, and landscape diversity measures. Dependent variables are measured by accelerometers, pedometers, behavior mapping, videorecording, and social surveys. Results demonstrate the strength of multimethod strategies mixing objective, quantitative measures with qualitative measure s that help explain the quantitative results. The authors argue that such strategies are more likely to both attract public attention as well as provide policy makers with evidence.