This book is considered to provide a sober, balanced, and scholarly examination of the evidence that bears on the role of genetic and environmental factors in the determination of group differences in ability in the United States. The first chapter provides something of the background and recent history of the concern with racial-ethnic differences in intellectual performance in the U.S. The three chapters that complete the first part of the book are said to be intended to clarify some of the issues of definition and measurement surrounding three of the key concepts on which the controversy focuses--race, intelligence, and heritability. Following this, the four chapters in the second part of the book review the body of evidence relevant to the major empirical question of concern: What are the relative roles of the genes and the environment in accounting for differences in average performance of different U.S. racial-ethnic groups on tasks purporting to measure intellectual capacity? In the concluding section, whatever theoretical conclusions the authors state as appearing to be justified by the data and what purportedly appear to be--and not to be--legitimate implications of these conclusions for the formulation of social policy are set down. (Author/JM)