In a study of the relationships between school racial composition and intergroup hostility in 123 desegregated elementary schools, four measures of racial hostility were considered: (1) white attitudes toward desegregation; (2) whites' friendliness toward blacks as perceived by blacks; (3) white attitudes toward voluntary social interaction with blacks; and (4) teacher estimates of the level of intergroup conflict in the school. The results indicated significant nonlinear relationships between the black percentage of white hostility, but did not show black percentage as significant predictor of white attitudes toward contact with blacks. It was found also that maximum hostility occurs in schools between 40 percent to 60 percent black. In conclusion, it was suggested that the hostility of white students toward blacks might best be minimized by placing white students in predominantly white schools or in predominantly black schools. (JCD)