Using the data from the Educational Opportunities Survey (1965), this report shows shows that for sixth grade students, 24 percent of the total differences among students in their academic achievement is the maximum national value that can be associated with their membership in one of six racial-ethnic groups (Indian, Mexican, Puerto-Rican, Negro, Oriental, or white). This relationship prevails before the allocation of these groups to different social conditions has been taken into account. After a variety of social condition variables have been accounted for, such as the social and economic well-being of the family, the presence or absence of key family members, the students and parents aspirations for his schooling, etc., the precentage of difference dropped to 1.2. Similar results were obtained for other grade levels and for each region of the country. Hence, no inferences can be made about the "independent effect" of membership in a particular racial-ethnic group on academic achievement because of the influence of a variety of social conditions. Other analyses show that variables pertaining to the motivational and attitudinal aspects of family life play a greater role in academic achievement than either racial-ethnic group membership, social class membership, or the type of school attended. (Author/JW)