Intellectual Disabilities


Our nation’s special education law, the Individuals with Disabilities Education Act (IDEA) defines intellectual disability as...

“...significantly subaverage general intellectual functioning, existing concurrently with deficits in adaptive behavior and manifested during the developmental period, that adversely affects a child's educational performance.”

[34 Code of Federal Regulations §300.8(c)(6)]


Intellectual Disability, sometimes called a cognitive disability, is a newer term in IDEA. Until October 2010, the law used the term mental retardation.In October 2010, President Obama signed Rosa’s Law, changing the term to be used in the future to “intellectual disability.” The definition of the term itself did not change.

Sometimes intellectual disability is also referred to as developmental disabilitywhich is a broader term that includes ASD (autism spectrum disorder), epilepsy, cerebral palsy, developmental delay, fetal alcohol syndrome (FASD), and other disorders that occur during the developmental period (birth to age 18).

(Center for Parent Information and Resources,CPIR, 2017)
(The ARC of the United States, 2018)


Additionally, an intellectual disability may possibly co-occur with other disabilities such as Autism Spectrum Disorder (ASD), Fetal Alcohol Syndrome (FASDs), cerebral palsy, epilepsy, ADHD, and depression and anxiety disorders.


Intellectual disability is the most common developmental disability. Approximately 7-8 million people in the United States have an intellectual disability, translating to 1 in 10 families that are affected. More than 425,000 children (ages 3-21) have some level of intellectual disability and receive special education services in public school under this category in IDEA, the nation’s special education law. In fact, 7% of children who need special education have some form of intellectual disability.

(CPIR, 2017)


The Diagnostic and Statistical Manual of Mental Disorders (DSM-5) published by the American Psychiatric Association states the following three criteria must be met for a diagnosis of intellectual disability/developmental disorder:

  1. Deficits in intellectual functions, such as reasoning, problem solving, planning, abstract thinking, judgment, academic learning, and learning from experience, confirmed by both clinical assessment and individualized, standardized intelligence testing.
  2. Deficits in adaptive functioning that result in failure to meet developmental and sociocultural standards for personal independence and social responsibility. Without ongoing support, the adaptive deficits limit functioning in one or more activities of daily life, such as communication, social participation, and independent living, across multiple environments, such as home, school, work, and community.
  3. Onset of intellectual and adaptive deficits during the developmental period.

(DSM-5, 2017)

Intellectual disability is a disability characterized by significant limitations in both intellectual functioning and in adaptive behavior, which covers many everyday social and practical skills. This disability originates before the age of 18.

(American Association on Intellectual and Developmental Disablities, AAIDD)

Intellectual disabilities are diagnosed by looking at two things: the ability of a person’s brain to learn, think, solve problems, and make sense of the work (called IQ or intellectual functioning); and whether the person has the skills he or she needs to live independently (called adaptive behavior or adaptive functioning).

Intellectual functioning, or IQ, is usually measured by a test called an IQ test. The average score is 100. People scoring below 70 to 75 are thought to have an intellectual disability. To measure adaptive behavior, professionals look at what a child can do in comparison to other children of his or her age. Certain skills important to adaptive behavior include daily living skills, communication skills, and social skills.

Providing services to help individuals with intellectual disabilities has led to a new understanding of how we define the term. After the initial diagnosis is made, the individual’s strengths and weaknesses are examined in addition to how much support or help is needed to participate at home, in school, and in the community. This approach gives a realistic picture of each individual. It also recognizes that the “picture” can change. As the person grows and learns, their ability to get along in the world grows as well.

(CPIR, 2017)


The most common causes of intellectual disabilities are:

  • Genetic conditions, such as Down syndrome, fragile X syndrome, and phenylketonuria (PKU)
  • Problems during pregnancy, such as a baby’s cells dividing irregularly as it grows, a mother who gets an infection such as rubella while pregnant, or drinking during pregnancy
  • Problems at birth, such as the baby not getting enough oxygen
  • Health problems: diseases like whooping cough, the measles, or meningitis can cause intellectual disabilities. They can also be caused by extreme malnutrition, not getting enough medical care, or by being exposed to poisons like lead or mercury.

(CPIR, 2017)


There are many signs of an intellectual disability including:

  • Sit up, crawl or walk later than other children
  • Learn to talk later, or have trouble speaking
  • Find it hard to remember things
  • Not understand how to pay for things
  • Have trouble understanding social rules
  • Have trouble seeing the consequences of their actions
  • Have trouble solving problems
  • Have trouble thinking logically

(CPIR, 2017)


There is no cure for intellectual disabilities. However, most children with an intellectual disability can learn to do many things, often with a little more time and support than other children.

When a baby is born with an intellectual disability, help is available immediately. Shortly after a confirmed diagnosis, early intervention services are available and mandated for infants and toddlers up to age 3 by IDEA. An individualized family services plan (IFSP) will be developed to describe a child’s unique needs and the services they will receive for those needs. For school age children, special education services are available to develop an Individualized Education Program (IEP), similar to an IFSP, to address needs and services for a child.

Supports and services for adults with intellectual disabilities focus on their daily lives: justice, housing, recreation, employment, health care, etc. Case managers can help a person apply for Medicaid in order to get a variety of supports including daily living needs, health care, and long term care services and supports. Vocational programs, job coaching, day programs, and residential options are also resources that help promote the interests and well-being of a person with an intellectual disability. Supports can be provided by a parent, sibling, friend, teacher, or other person (i.e. co-worker) in many settings. A location or setting on its own is not considered a support.

(CPIR, 2017)
(ARC, 2018)


A child with an intellectual disability can do well in school but is likely to need the individualized help that’s available as special education and related education services. The level of help and support that’s needed will depend upon the degree of intellectual disability involved.

General education. It’s important that students with intellectual disabilities be involved in, and make progress in, the general education curriculum.

Supplementary aids and services. Given that intellectual disabilities affect learning, it’s often crucial to provide supports to students with ID in the classroom. This includes making accommodations appropriate to the needs of the student. Supplementary aids and services are supports that may include instruction, personnel, equipment, or other accommodations.

Adaptive skills. Many children with intellectual disabilities need help with adaptive skills, which are skills needed to live, work, and play in the community. These skills include:

  • Communicating with others
  • Taking care of personal needs (dressing, bathing, going to the bathroom)
  • Health and safety
  • Home living (helping to set the table, cleaning the house, or cooking dinner)
  • Social skills (manners, knowing the rules of conversation, getting along in a group, playing a game)
  • Reading, writing, and basic math
  • Skills that will help them in the work place

Transition planning. It’s extremely important for families and schools to begin planning early for the student’s transition into the world of adulthood. The sooner transition planning begins, the more can be accomplished before the student leaves secondary school. IDEA requires that at the latest, transition planning for students with disabilities must begin no later than 16.

(CPIR, 2017)

Strategies for Teachers

Many of these strategies are universal, improving the learning experience of all students in your classroom.

  • Recognize that you can make an enormous difference in this student’s life! Find out what the student’s strengths and interests are, and emphasize them. Create opportunities for success.
    If you are not part of the student’s IEP team, ask for a copy of his or her IEP. The student’s educational goals will be listed there, as well as the services and classroom accommodations he or she is to receive. Talk to others in your school (e.g., special educators), as necessary. They can help you identify effective methods of teaching this student, ways to adapt the curriculum, and how to address the student’s IEP goals in your classroom.
  • Be as concrete as possible. Demonstrate what you mean rather than giving verbal directions. Rather than just relating new information verbally, show a picture. And rather than just showing a picture, provide the student with hands-on materials and experiences and the opportunity to try things out.
  • Break longer, new tasks into small steps. Demonstrate the steps. Have the student do the steps, one at a time. Provide assistance, as necessary. Provide multiple opportunities to practice skills in a variety of contexts and applications.
  • Give students immediate feedback.
  • Teach the student life skillssuch as daily living, social skills, and occupational awareness and exploration, as appropriate. Involve the student in group activities or clubs.
  • Work together with the student’s parents and other school personnel to create and implement an IEP tailored to meet the student’s needs. Regularly share information about how the student is doing at school and at home.

Strategies for Parents

  • Learn about intellectual disability. The more you know, the more you can help yourself and your child.
  • Be patient, be hopeful. Your child, like every child, has a whole lifetime to learn and grow.
  • Encourage independencein your child. For example, help your child learn daily care skills, such as dressing, feeding him or herself, using the bathroom, and grooming.
  • Give your child chores. Keep her age, attention span, and abilities in mind. Break down jobs into smaller steps. For example, if your child’s job is to set the table, first ask her to get the right number of napkins. Then have her put one at each family member’s place at the table. Do the same with the utensils, going one at a time. Tell her what to do, step by step, until the job is done. Demonstrate how to do the job. Help her when she needs assistance.
  • Give your child frequent feedback. Praise your child when he or she does well. Build your child’s abilities.
  • Find out what skills your child is learning at school. Find ways for your child to apply those skills at home. For example, if the teacher is going over a lesson about money, take your child to the supermarket with you. Help him count out the money to pay for your groceries. Help him count the change.
  • Find opportunities in your community for social activities, such as scouts, recreation center activities, sports, and so on. These will help your child build social skills as well as to have fun.
  • Talk to other parentswhose children have an intellectual disability. Parents can share practical advice and emotional support.
  • Meet with the school and develop an IEP to address your child’s needs. Keep in touch with your child’s teachers. Offer support. Find out how you can support your child’s school learning at home.

(CPIR, 2017)


American Association of Intellectual and Developmental Disabilities (AAIDD)
8403 Colesville Road, Suite 900
Silver Spring, MD 20910

Since 1876, the American Association of Intellectual and Developmental Disabilities has been providing worldwide leadership in the field as the oldest and largest disciplinary organization of professionals and others concerned about intellectual and developmental disabilities. AAIDD promotes progressive policies, sound research, effective practices, and universal human rights for people with intellectual and developmental disabilities.

The Arc of the United States (ARC)
1825 K Street, NW,
Suite 1200
Washington, DC 20006 

With 1,000 chapters in the U.S., The Arc of the United States is the country's largest voluntary organization committed to the welfare of children and adults with mental retardation and their families. This organization provides information about educational campaigns and other materials that are helpful to parents and educators. Also, you can connect with a local chapter through the website.

Best Buddies International
100 Southeast Second St., Suite 2200
Miami, FL 33131

Best Buddies International is a nonprofit organization dedicated to establishing a global volunteer movement that creates opportunities for one-to-one friendships, integrated employment, leadership development, and inclusive living for individuals with intellectual disabilities. The community served includes, but is not limited to, people with Down Syndrome, autism, Fragile X, Williams Syndrome, cerebral palsy, traumatic brain injury, and other undiagnosed disabilities. Best Buddies is the world’s largest organization dedicated to ending the social, physical, and economic isolation of the 200 million people with intellectual and developmental disabilities (IDD). Our programs empower the special abilities of people with IDD by helping them form meaningful friendships with peers, secure successful jobs, live independently, improve public speaking, self-advocacy and communication skills, and feel valued by society.

Last updated December 2019.