Special Ed Resources Support for Special Needs Child

Special Education Resources

Special education special needs resources
Special EducationTeaching GamesTipsDictionary Products Bookstore

Looking for something in particular?

More search options

Special Education Information: Disability Definitions: Definition of Intellectual Disabilities

Definition of Mental Retardation

Fact Sheet Number 8 (FS8), January 2001
National Information Center for Children and Youth with Disabilities


People with mental retardation are those who develop at a below average rate and experience difficulty in learning and social adjustment. The regulations for the Individuals with Disabilities Education Act (IDEA) provide the following technical definition for mental retardation:

"Mental retardation means 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."

"General intellectual functioning" is typically measured by an intelligence test. Persons with mental retardation usually score 70 or below on such tests. "Adaptive behavior" refers to a person's adjustment to everyday life. Difficulties may occur in learning, communication, social, academic, vocational, and independent living skills.

Mental retardation is not a disease, nor should it be confused with mental illness. Children with mental retardation become adults; they do not remain "eternal children." They do learn, but slowly, and with difficulty.

Probably the greatest number of children with mental retardation have chromosome abnormalities. Other biological factors include (but are not limited to): asphyxia (lack of oxygen); blood incompatibilities between the mother and fetus; and maternal infections, such as rubella or herpes. Certain drugs have also been linked to problems in fetal development.


Some studies suggest that approximately 1% of the general population has mental retardation (when both intelligence and adaptive behavior measures are used). According to data reported to the U.S. Department of Education by the states, in the 1998-99 school year, 610,445 students ages 6-21 were classified as having mental retardation and were provided special education and related services by the public schools. This figure does not include students reported as having multiple disabilities or those in non-categorical special education pre-school programs who may also have mental retardation.


Many authorities agree that people with mental retardation develop in the same way as people without mental retardation, but at a slower rate. Others suggest that persons with mental retardation have difficulties in particular areas of basic thinking and learning such as attention, perception, or memory. Depending on the extent of the impairment -- mild, moderate, severe, or profound -- individuals with mental retardation will develop differently in academic, social, and vocational skills.


Persons with mental retardation have the capacity to learn, to develop, and to grow. The great majority of these citizens can become productive and full participants in society.

Appropriate educational services that begin in infancy and continue throughout the developmental period and beyond will enable children with mental retardation to develop to their fullest potential.

As with all education, modifying instruction to meet individual needs is the starting point for successful learning. Throughout their child's education, parents should be an integral part of the planning and teaching team.

In teaching persons with mental retardation, it is important to:

  • Use concrete materials that are interesting, age-appropriate, and relevant to the students;

  • Present information and instructions in small, sequential steps and review each step frequently;

  • Provide prompt and consistent feedback;

  • Teach these children, whenever possible, in the same school they would attend if they did not have mental retardation;

  • Teach tasks or skills that students will use frequently in such a way that students can apply the tasks or skills in settings outside of school; and

  • Remember that tasks that many people learn without instruction may need to be structured, or broken down into small steps or segments, with each step being carefully taught.
Children and adults with mental retardation need the same basic services that all people need for normal development. These include education, vocational preparation, health services, recreational opportunities, and many more. In addition, many persons with mental retardation need specialized services for special needs. Such services include diagnostic and evaluation centers; special early education opportunities, beginning with infant stimulation programs and continuing through preschool; and educational programs that include age-appropriate activities, functional academics, transition training, and opportunities for independent living and competitive employment to the maximum extent possible.


Arc. (1998). Introduction to mental retardation (Rev. ed.). Silver Spring, MD: Author. [Telephone: (301) 565-3842.]

Smith, R. (Ed.). (1993). Children with mental retardation: A parents' guide. Rockville, MD: Woodbine House. [Telephone: 1-800-843-7323.]

Trainer, M. (1991). Differences in common: Straight talk on mental retardation, Down syndrome, and life. Rockville, MD: Woodbine House. (See telephone number above.)

Updated January 2001

This fact sheet is made possible through Cooperative Agreement #H326N980002 between the Academy for Educational Development and the Office of Special Education Programs. The contents of this publication do not necessarily reflect the views or policies of the Department of Education, nor does mention of trade names, commercial products or organizations imply endorsement by the U. S. Government.

This information is in the public domain unless otherwise indicated. Readers are encouraged to copy and share it, but please credit the National Information Center for Children and Youth with Disabilities (NICHCY).

National Information Center for Children and Youth with Disabilities
P.O. Box 1492
Washington, DC 20013
1-800-695-0285 (Voice/TT)
E-mail: nichcy@aed.org
Web site: http://www.nichcy.org/

Print this page