Integrated schools may still be substantively segregated if friendships fall within race. Drawing on contact theory, this study tests whether school organization affects friendship segregation in a national sample of adolescent friendship networks. The results show that friendship segregation peaks in moderately heterogeneous schools but declines at the highest heterogeneity levels. As suggested by contact theory, in schools where extracurricular activities are integrated, grades tightly bound friendship, and races mix within tracks, friendship segregation is less pronounced. The generally positive relation between heterogeneity and friendship segregation suggests that integration strategies built on concentrating minorities in large schools may accentuate friendship segregation.