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What are Intellectual and Developmental Disabilities?

Studies show that somewhere between 1-3% of Americans have an intellectual or developmental disability, approximately 4.6 million people nationwide and 33,000 in King County. 

Intellectual and developmental disabilities are characterized by limitations in two areas: 

  • Cognitive functioning which includes things like learning, reasoning, thinking abstractly, generalizing learning in a variety of settings, and problem solving 
  • Adaptive behavior which includes things like social interactions, receptive and expressive language, self-direction and daily practical skills

To be considered a developmental disability, the disability must have occurred before the person’s 18th birthday. Developmental disabilities include Intellectual Disability, Down syndrome, Autism, Cerebral Palsy, Epilepsy, and other similar conditions. Disabilities are not always visible, especially intellectual and developmental disabilities. The way disability impacts an individual varies for each person, by the situation, and the environment the individual is in.

Disability is a natural part of life but it does not define the individual. The Arc of King County believes that people with intellectual and developmental disabilities have the right to live, learn, work, and play in the community. We envision an inclusive world where individuals with intellectual and developmental disabilities thrive as equal, valued, and active community members. Each individual has many assets and contributes to the community and workforce. The Arc strives to break down the barriers faced by people with intellectual and developmental disabilities to live a life of their choosing in the community. Barriers are not only physical barriers, but come in the form of policies, lack of services, negative perceptions, and destructive attitudes.

Would you like to learn more about disability awareness and acceptance?  Looking for ways to empower individuals with disabilities? Connect with the Community Change Champions program. 

Check out our Mission and Vision page to learn more about The Arc of King County. 

Also, our Resource Guide is designed to help individuals with intellectual and developmental disabilities and their families in King County.

Sources include: Larson, 2000 and The Arc website,