This book about the g factor has its origin in the aftermath of an almost booklength article (my 77th publication) that I wrote almost thirty years ago, titled "How Much Can We Boost IQ and Scholastic Achievement?” and published in the Harvard Educational Review in 1969. It had five main themes: (1) the malleability of IQ (or the latent trait it measures) by special psychological and educational interventions in the course of children’s mental development; (2) the heritability of IQ; (3) social class and race differences in IQ; (4) the question of cultural bias in mental tests; (5) the need for universal education to tap types of learning ability that are relatively unrelated to IQ in order to achieve the benefits of education for all children throughout the wide range of abilities in the population. It made four main empirically based claims: (1) individual differences in IQ are largely a result of genetic differences but environment also plays a part; (2) the experimental attempts to raise the IQs of children at risk for low IQ and poor scholastic performance by various psychological and educational manipulations had yielded little, if any, lasting gains in IQ or scholastic achievement; (3) since most of the exclusively cultural-environment explanations for racial differences in these important variables were inconsistent and inadequate, genetic as well as environmental factors should be considered; (4) certain abilities, particularly rote-learning and memory, had little relation to IQ, which suggested that these non-IQ abilities could to some extent compensate for low IQ to improve the benefits of schooling for many children at risk for failure under traditional classroom instruction.