Although parental choice of secondary schools is a subject of considerable public and academic interest, there has been relatively little research on the extent to which choice is undermining the traditional role of geographically defined school catchments. This paper, therefore, uses data provided by a case-study local education authority to examine the nature and scale of pupil flows across catchment boundaries. It does so by adopting a form of Geographic Information System as the principal research tool. The results show over (...) a third of Year 7 pupils moving to schools other than their catchment comprehensive. Interestingly, the inner-city catchments were the most permeable: by contrast, children in middle class and rural areas were the least likely to enter a school outside their local area. (shrink)