ARTHUR R. JENSEN is Professor Emeritus of Educational Psychology, Graduate School of Education, University of California, Berkeley. During the 40 years of his tenure at Berkeley, he has been a prolific researcher in the psychology of human learning, individual differences in cognitive abilities, psychometrics, behavioral genetics, and mental chronometry. His work, published in six earlier books and some 400 articles in scientific and professional journals, has placed him among the most frequently cited figures in contemporary psychology.