In these twelve stimulating essays, Kagan thoughtfully examines the development of the child--the growth of the infant's mind, the implications of cognitive leaps-forward on early adolescent attitudes, the psychology of sex differences, the meaning of maturity, and other critical issues. As in other collections of separately published papers, there are stylistic chinks: the same day-care study, referred to in several papers, is introduced each time as the first. And Kagan, writing for a professional audience, assumes the reader's familiarity with terms like myelination, the salience of the mother, and assimilation. But such reservations are trifling; the essays, coming from one of our foremost child development theorists, are invigorating. Kagan can demonstrate why the speech mechanisms of girls may mature earlier than boys', suggest a relationship between memory development and the eight-month infant's separation anxiety, or gently skewer his colleagues' myopia: ""Psychology has chosen to call this extra added mysterious something 'reinforcement,' much as eighteenth century chemists chose to label their unknown substance 'phlogiston.'"" In perhaps the most exciting paper, ""The Enigma of Intelligence,"" he not only dispatches Jensen to the distant sidelines but also establishes the shakiness of the concept of intelligence, indicates what the valuing of IQ-test-skills does to the general population, and reminds that social class remains the single best predictor of school performance. Always, the key questions reflect the strong ethical grounding on which his work is based, and the acute central observations extend beyond his academic field of expertise: ""The most profound change in American and Western Europe during recent decades does not involve attitudes surrounding sexuality, permissiveness toward drugs, or the celebration of sensuality, but rather the assumption that authority is tainted and is not to be awarded any special wisdom, virtue, or benevolence."" Uncommonly clearheaded and resourceful.