He said it before and he will say it again: IQ is 70 percent heritable, and IQ is a fair measure of intelligence. Last year Jensen addressed his critics in Bias in Mental Testing, a scholarly tome offering the reader a crash course in factor analysis and analysis of variance. This year he has chosen a popular approach, writing for general readers with a minimum of technical explanations and with assorted addenda to extend his arguments. Essentially he defends the Stanford-Binet and Wechsler tests against charges of bias, and explains quite well the meaning of test reliability, stability, and predictive validity. He contends, again, that objective tests serve lower socioeconomic groups and minorities better, as regards admission to college or professions, than would be the case in the absence of tests. He offers no explanation for the existence of the genetic differences in intelligence he finds between whites and blacks, and he attacks the environmentalists' various arguments (teacher expectation, cultural bias, the ""black experience,"" etc.). He concedes, however, that environmental factors may be additive and could account for a third of the average 15 pt. IQ difference in scores between blacks and whites. Jensen has modified somewhat his criticism of early intervention programs for pre-schoolers; some studies, he states, should continue. He even concludes with a reasonable quotation from several psychologists to the effect that intragroup differences vastly exceed intergroup differences; and that test inadequacies, environment, and genes not only interact, but a ""sensible person's position might well differ for different abilities, for different groups, and for different tests."" Jensen is still vexing in his glib statements about brain size correlated with intelligence, some remarks on the improbability of malnutrition affecting current US infants, a pious condemnation-cum-defense of Burt--to name a sample. Readers should also check out Leon Kamin's arguments (in Eysenck, The Intelligence Controversy, p. 260) with regard to the twin studies that are the major bulwark in the genetic arguments. Jensen is nobody's fool and he has modified his position--somewhat.