In the 16 years since the publication of the second edition of this volume, psychological theory and research in mental retardation has continued to expand and extend scientific, theoretical, and clinical understanding of this most complex and challenging human condition. Explicit effort has been made to translate theory and research into useful and efficacious assessment, intervention, prevention, and policy actions. This third edition provides an opportunity to critique major conceptual developments and empirical research in an effort to stimulate further behavioral research of practical,...