Colleges have talked for decades about the educational benefits of diversity on their campuses without offering much research to show how students are affected by exposure to members of other racial and ethnic groups. In an effort to fill that gap, James Sidanius, a professor of psychology and of African and African-American studies at Harvard University, led a team of researchers in a long-term study of about 2,000 students who entered the University of California at Los Angeles (UCLA) in the fall of 1996. The students were surveyed in the summer before they entered UCLA, at the end of their freshman year, and again each year until graduation or the end of their fifth year in college. Mr. Sidanius and his co-authors describe their results in a new book, "The Diversity Challenge: Social Identity and Intergroup Relations on the College Campus", published by the Russell Sage Foundation. The author interviewed Mr. Sidanius, who noted that book concludes that cultural diversity and multicultural practices neither significantly changed student ethnic identifies and views, nor heightened ethnic conflict and/or separation on campus; and the clear indication of negative influence of ethnically oriented student organizations.