Aspects of both educational development and multicultural interrelationships are frequently related to school ethnic composition, with arguments that ethnically segregated schools both retard the development of multiethnic understanding and influence educational performance. In this article we employ data on their ethnic composition to portray the extent of segregation in English secondary schools in 2001, using a novel graphical method to explore its nature and spatial variation. We find substantial segregation on ethnic criteria in some places. Nevertheless, over the country as a whole, attendance at substantially mono-ethnic schools is not the norm for members of the non-white groups (though it is for whites in many areas). Half of all non-white secondary students in England attended schools where more than 75 percent of the total enrolment comprised whites.