Introduction. 1. Science, Society, and Mental Retardation, A History. 2. Neurogenesis, Neuronal Migration, Maturation, and Function: Insights into Learning and Memory. 3. Structural Brain Anomalies and Neural Tube Defects. 4. Mental Retardation Associated with Dysmorphology, Growth Retardation, or Overgrowth. 5. Mental Retardation Associated with Other Neurological Defects. 6. Mental Retardation that Develops Aftera Period of Norma Cognition. 7. Nonsyndromic Mental Retardation, Autism, and Language Deficits. 8. Genomics, Functional Genomics, and Epigenetics: Relevance to Mental Retardation. 9.Abstract: Introduction. 1. Science, Society, and Mental Retardation, A History. 2. Neurogenesis, Neuronal Migration, Maturation, and Function: Insights into Learning and Memory. 3. Structural Brain Anomalies and Neural Tube Defects. 4. Mental Retardation Associated with Dysmorphology, Growth Retardation, or Overgrowth. 5. Mental Retardation Associated with Other Neurological Defects. 6. Mental Retardation that Develops After a Period of Norma Cognition. 7. Nonsyndromic Mental Retardation, Autism, and Language Deficits. 8. Genomics, Functional Genomics, and Epigenetics: Relevance to Mental Retardation. 9