This new reference provides a comprehensive overview of intellectual and developmental disabilities, incorporating multiple perspectives and disciplines (including developmental neuroscience, genetics, psychiatry, and psychology) with a multifaceted approach, offering readers appreciation for the richness of the population and field. It provides readers with an understanding of the developmental, biological, and behavioral aspects of developmental disabilities with the aim of understanding their causes, the differences between disabilities, and familiarity with the prognosis and developmental outcomes for children diagnosed with various developmental disabilities.