Segregation in education has major social repercussions. The prejudice that many young African-Americans experience causes them undue stress which has been proven to undermine cognitive development. Eric Hanushek and his co-authors have considered racial concentrations in schools, and they find large and important effects. Black students appear to be systematically and physically hurt by larger concentrations of black students in their school. These effects extend neither to white nor to Hispanic students in the school, implying that they are related to peer interactions and not to school quality. Moreover, it appears that the effect of black concentrations in schools is largest for high-achieving black students.