Developmental disabilities or neurodevelopmental disabilities (includes intellectual disability) are a diverse group of chronic disorders that begin at anytime during the development process (including conception, birth, and growth) up to 22 years of age and last throughout an individual's lifetime. Major disabilities include intellectual disabilities, learning disabilities, communication disorders, autism spectrum disorders, cerebral palsy, and neural tube defects. We provide an introduction and review epidemiology of major disabilities and have also gathered international research from United States, Australia, Ghana, Jordan, Ireland, Italy and India on various aspects of intellectual and developmental disability, which we hope will be of interest to our readers.