This research was stimulated by concern over the tragically high pedestrian accident involvement rates of children between the ages of 4 and 9 years. The objective was to discover whether young children hold naïve conceptions of speed and whether the nature of their concepts could be a causal factor in the accident equation. Road traffic engineers have tended to blame the impulsive behaviour of children for their accidents and have attempted to counter this with 'magic formula' type crossing codes. However, the authors have found that children do hold a range of beliefs regarding the concept of speed that would undoubtedly place them at risk if utilized in crossing episodes because their naive conceptions are likely to be at variance with those held by vehicle drivers.