The admissions policies of 47 colleges and universities were studied to consider the issue of racial and ethnic discrimination in undergraduate admissions. The Center for Equal Opportunity asked schools for data about students' application status, racial and ethnic group membership, verbal and mathematics Scholastic Assessment Test scores, and high school grade point average and class rank. Findings indicate that the average difference in academic credentials among those admitted--whether measured by test scores or grades and high school class rank, between blacks and whites, and to a lesser degree, between Hispanics and whites--is very large. There are few such differences between whites and Asians. Racial and ethnic preferences play a far more important role in admissions than has previously been acknowledged. Blacks have far greater probabilities of admission than do similarly qualified whites at a large variety of schools. Hispanics have substantially greater probabilities of admission than do whites, and Asians have similar probabilities of admission. All of these conclusions take into account both test scores and grades. Racial and ethnic preferences in admissions are pervasive and national in scope, and are not restricted to any region of the country. The more selective colleges and universities are more likely to use preferences for black applicants than are their less selective counterparts, but few colleges and universities use no preferences at all. Fewer schools have preferences for Hispanics, and only a handful have preferences for Asians. Appendixes contain the odds ratios for the analyses and the logistic regression equation estimating the probability of admission to eight schools. (Contains 19 tables, 15 figures, and 46 endnotes.) (SLD)