Investigating the impact of a smart growth community on the contexts of children's physical activity using Ecological Momentary Assessment

► We compare physical activity contexts between smart growth (SG) and conventional communities. ► We use Ecological Momentary Assessment with electronic surveys delivered through mobile phones. ► SG children are more physically active with friends, close to home, and at walkable locations. ► Over time, SG children report less physical activity at home and in high traffic locations. ► Urban design may influence where and with whom children engage in physical activity.