Objectives: First, to measure the speeds of vehicles with and without children on the footpath, and second to compare these with drivers' estimates of how fast they would go in these conditions. Design: The speeds of vehicles in three conditions: control (no children present), children playing with a ball on the footpath, and children waiting to cross the road, were measured using speed tubes during two 55 minute sessions. Drivers' estimates of their speeds were measured with a questionnaire. Setting: Speeds were measured on a main road in Auckland, New Zealand. The questionnaire was conducted at another time with drivers stopping for petrol approximately 500 metres from the measurement site. Subjects: A total of 1446 speed measurements were taken and 93 drivers‘ questionnaire responses were analysed. Results: The mean free speed of vehicles in the control condition was 55.60 kph, with drivers‘ estimates being 56.37 kph. When children were playing with a ball the measured speed was 54.29 kph and the estimated speed 39.27 kph. When children were waiting to cross the measured speed was 52.78 kph, estimated speed 34.02 kph. Analyses indicated that there were significant differences between measured and estimated speeds. Conclusions: New Zealand drivers make inadequate speed adjustments in the presence of children, despite probably believing they do so. Establishing specific rules about appropriate speeds around children and highlighting to drivers the discrepancy between their attitudes and behaviour are two intervention strategies suggested.