Utilizing a minimum of technical terminology, this eight-chapter monograph introduces beginning psychology students to the basic concepts of Piaget's theory of mental development and to its application by parents and teachers. As an aid to learning, each of the concepts discussed is illustrated by black-and-white drawings which can be reproduced as transparencies. Chapter I provides information for the instructor on the use of the book as well as an introductory note for the student. It goes on to provide information about Jean Piaget and summarize his fundamental principles of assimilation, accommodation, and equilibrium. Chapters II through V describe the four cognitive stages and the associated sub-stages in Piaget's mental development model; these four stages are the sensorimotor, preoperational, concrete operational, and formal operational stages. Chapter VI then presents four self-evaluation exercises that can be used independently by the students to test their learning. Chapter VII presents general rules for applying Piaget's theory and outlines the behavioral characteristics that adults can expect of children at each developmental level. Finally, Chapter VIII provides an extensive bibliography. (JP)