This volume culminates more than 40 years of theory and research in the field of mental retardation. As a champion of developmental approach, Edward Zigler emphasizes the importance of personality and motivation factors in understanding the behavior of individuals with mental retardation. He argues that personality, emotions, and motivation should be recognized as important determinants in the performance of retarded individuals just as they are with nonretarded individuals. In addition to summarizing Zigler's developmental formulation of mental retardation, this volume integrates the work of several major researchers as it elaborates the relationship between personality-motivation and cognitive performance. Empirical work is augmented with practical implications for professionals involved in identifying, educating, and integrating mentally retarded individuals into society. As there is no other single publication that combines the issues, theories, and research with practical implications, this book makes a significant contribution to the field of mental retardation.