Part I: Understanding mental retardation -- 1. Definition, measurement, and labeling: Old concepts and new visions -- 2. Etiology, prevention, and growing issues in medical treatment -- 3. Learning, mental illness, and norm-violating behavior -- Part II: Social care and treatment -- 4. New foundations -- 5. Childhood and adolescence: Changing perspectives and programs -- 6. Adult services: The great unmet need -- 7. Institutions and deinstitutionalization: A shifting emphasis.