This paper describes a study of existing distributions of elementary schools and dwellings, main roads, and local shops, for two Hertfordshire, England, towns. The effects of these factors on the mode of travel of school children, road accidents to child pedestrians, and the shape and mobility of catchment areas were all investigated. Based on the information gained, a reassessment is made of some long-standing assumptions regarding catchment areas; a number of propositions are yielded for use both in reaching planning decisions and in predicting the consequences for the primary education system of decisions on other considerations. (FS)