A study was conducted in two desegregated high schools in order to test Sherif's theory that intergroup conflict can be eliminated when the groups strive for superordinate goals. The specific question examined in the study was: To what extent do members of an ethnic group enlarge their conception of their own in-group to include members of another ethnic group (out-group) after having had contact with the out-group members in work teams that are striving for superordinate goals? It was posited that if an in-group enlarged its self concept to include members of the out-group, then greater integration would have been achieved, supporting Sherif's theory. In one of the high schools, the classroom grouping procedures and reward structure were changed. Students of different ethnic groups (Mexican American and white) were required to interact in a cooperatively interdependent manner to achieve superordinate goals. The other high school served as a comparison group. Students in both schools were tested at the beginning and end of the school year. A comparison of change scores in the two schools did not support Sherif's theory. (Author/GC)