What are Intellectual and Developmental Disabilities?

Intellectual and developmental disabilities (IDDs) are disorders that are usually present at birth and that negatively affect the trajectory of the individual’s physical, intellectual, and/or emotional development. Many of these conditions affect multiple body parts or systems. As of 2016, 7.37 million people in the United States had intellectual or developmental disabilities. Intellectual disability starts any time before a child turns 18 and is characterized by problems with both intellectual functioning or intelligence – which includes the ability to learn, reason, problem-solve, and other skills – and adaptive behavior, which includes everyday social and life skills.

The term "developmental disabilities" is a broader category of often lifelong disability that can be intellectual, physical, or both. "IDD" is the term often used to describe situations in which intellectual disability and other disabilities are present. Examples of developmental disabilities include autism, behavior disorders, brain injury, cerebral palsy, Down syndrome, fetal alcohol syndrome, intellectual disability, and spina bifida. 

For more information, see the Developmental Disabilities Assistance and Bill of Rights Act of 2000 .