We have written this book in the hope of assisting the beginning student of Piaget. It is a brief introduction to his basic ideas and findings concerning the child's intellectual development. We hope that the book will be useful to students, particularly undergraduates, in psychology, education, and allied fields. The book may be used as supplementary reading, in whole or part, in courses dealing with child psychology, cognition, educational psychology, and so on. We hope, too, that the book may be read with profit by the general reader. - Preface.