An intellectual disability is a disability characterized by significant limitations in both intellectual functioning (reasoning, learning, and problem-solving) and in adaptive behavior (conceptual, social, and practical skills) that emerges before the age of 18. The American Association on Intellectual and Developmental Disabilities views intellectual disability as a functional interaction between an individual and the environment, rather than a static designation of a person’s limitations.
Degrees of intellectual disability are diagnosed as mild, moderate, severe, and profound. Approximately 85 percent of individuals with an intellectual disability fall into the mild category.