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What is I/DD?

Updated: May 12, 2023

Blog by LifeCourseOnline Partner AKALAKA


AKALAKA and its blog, Taking Care of Siblings, are here to support siblings of individuals with I/DD. What exactly does I/DD mean, and where does the term originate? We hope that we can answer these questions for you today, or help you learn more if you are already familiar with I/DD. I/DD is an acronym for “Intellectual and Developmental Disabilities,” which are defined during a person’s childhood, or before they are 22 years old (American Association on Intellectual and Developmental Disabilities). Developmental disabilities (DD) include language, learning, physical, or behavioral impairments. Common DD diagnoses include, but are not limited to, attention-deficit/hyperactivity disorder, autism spectrum disorder, cerebral palsy, hearing loss, and intellectual disability (Benjamin Zablotsky et al.). Intellectual disabilities include delays of mobility, speech, social cues, or memory (Centers for Disease Control and Prevention). In the United States, I/DD is a federally recognized term. We use the term I/DD here at AKALAKA because one of our goals is to help our members navigate federal disability services, primarily Medicaid’s Home and Community-Based Services (HCBS) Waiver program in each state. If you are caring for someone who qualifies for these services, you will often see the term "I/DD." You may also see the variations "ID," "DD," "ID/DD," or "D/ID." However, we should all be aware that some individuals or organizations may use terms other than I/DD. At AKALAKA, we always respect terms that someone chooses to describe their identity!

Although I/DD, as well as variations of this term, are now common in federal legislation, they are relatively recent developments in legislative history. It was not until 1975 that DD first appeared, specifically in the Developmentally Disabled Assistance and Bill of Rights Act (The Arc). Previous federal documentation had used terms such as “developmental abnormalities” and “mental retardation” (Federal Register). The Developmental Disabilities Assistance and Bill of Rights Act of 2000, which builds on the original law of 1975, provides federal funding to four resources: State Councils on Developmental Disabilities (Councils), State Protection and Advocacy Systems (P&As), University Centers for Excellence in Developmental Disabilities Education, Research & Services (UCEDDs), and Projects of National Significance (PNS) (Administration on Community Living). Many AKALAKA participants, adult siblings of persons with I/DD, have voiced their feelings of isolation on their journeys as siblings. We know what it feels like to be different from your peers and to struggle to manage care for yourself, your sibling(s), and even the rest of your family. Above all, we want you to know that you are not alone! About 17% of children aged 3 through 17 in the United States have intellectual or developmental disabilities, and 1 million of these children will become adults in the next decade (CDC). That’s a lot of potential siblings out there whom we hope will join the growing community of AKALAKA-- a community that is here to help you take care of yourselves, your siblings, and your communities.

Thank you to AKALAKA for partnering with LifeCourseOnline to bring us this content. This article was written by AKALAKA member Mary Landis Gaston. Check out the Taking Care of Siblings Blog and learn more about the AKALAKA community at Author Bio Mary Landis Gaston is an older sibling to her 13-year-old brother, James, who was born with significant intellectual and developmental disabilities. She currently lives in Chapel Hill, North Carolina, and is applying to medical schools to pursue academic medicine and become a pediatric specialist.

Works Cited

  • “Addressing the Causes and Effects of Intellectual and Developmental Disabilities.” The Arc, revised 2016,

  • “CDC’s Work on Developmental Disabilities.” Centers for Disease Control and Prevention, revised 13 September 2021,

  • “Definition of Intellectual Disability.” American Association on Intellectual and Developmental Disabilities, Accessed 28 November 2021.

  • “Facts About Intellectual Disability in Children.” Centers for Disease Control and Prevention, revised 24 August 2021,

  • “Rosa’s Law.” Federal Register, National Archives, 11 July 2017,

  • “The Developmental Disabilities Assistance and Bill of Rights Act of 2000.” U.S. Department of Health and Human Services, Administration for Community Living, modified 25 March 2021,

  • Zablotsky, Benjamin, et al. “Prevalence and Trends of Developmental Disabilities among Children in the US: 2009-2017.” Pediatrics, vol. 144, no. 4, 2019, doi:10.1542/peds.2019-0811.

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