Intellectual Disability
ICD-11 Classification for Intellectual Disability (6A00)
In ICD-11-MMS, Intellectual Disability is classified as 6A00, Disorders of Intellectual Development, under Neurodevelopmental Disorders. It is defined by significantly below-average intellectual and adaptive functioning originating in the developmental period, with severity coded mild, moderate, severe or profound, plus provisional categories where standardised testing is not yet feasible.
Every clinician needs the same anchor point: where does this child's developmental profile sit in the international classification? ICD-11 gives it a precise home.
In short
In ICD-11-MMS, Intellectual Disability is classified under 6A00 — Disorders of Intellectual Development, within the grouping of Neurodevelopmental Disorders. ICD-11 defines it as a group of aetiologically diverse conditions originating during the developmental period, characterised by significantly below-average intellectual functioning and adaptive behaviour that are approximately two or more standard deviations below the mean. Severity is specified — mild (6A00.0), moderate (6A00.1), severe (6A00.2), profound (6A00.3), with provisional and unspecified categories where standardised testing is not feasible.How ICD-11 frames the diagnosis
A key shift in ICD-11 is the term Disorders of Intellectual Development, replacing the older mental retardation nomenclature, and aligning the diagnostic logic with both intellectual and adaptive functioning rather than IQ alone. Severity is determined by assessing conceptual, social and practical adaptive domains, using appropriately normed and culturally valid instruments wherever available. Where age (early childhood) or co-occurring sensory, motor or communication impairment prevents valid standardised assessment, ICD-11 provides provisional categories — for example 6A00.4, Disorder of intellectual development, provisional — so that support is not delayed pending formal testing. This functional, developmental-period framing sits naturally alongside the WHO ICF model of functioning.When to refer
Refer a child for structured developmental assessment when global delay is evident across multiple domains, when adaptive skills lag persistently behind age expectations, or when parental and educational concern converge — rather than waiting for a single IQ figure. In early childhood, a global developmental delay descriptor is often more appropriate until reliable standardised intellectual assessment becomes feasible, typically beyond the preschool years.The Pinnacle way
At Pinnacle Blooms Network, a clinical AbilityScore® and any diagnosis are formed only at a Pinnacle Blooms Network centre, under qualified clinician care — never from an app, a form, or this page. Our clinician-administered structured assessment translates a child's profile into a clear baseline and a [practical support plan](/), drawing on 2.5 billion+ data points and 25 million+ therapy sessions across 70+ centres. Explore how the AbilityScore is established and cognitive and developmental therapy pathways.Trusted sources
WHO ICD-11 for Mortality and Morbidity Statistics, category 6A00, Disorders of intellectual development; CDC developmental milestone guidance; Indian Academy of Pediatrics; American Academy of Pediatrics paediatric developmental guidance.Next step — To establish a child's developmental baseline and severity profile with clinical rigour, [partner with a Pinnacle clinician](/).
This is general information, not a diagnosis — a clinical AbilityScore® and any diagnosis are formed only at a Pinnacle Blooms Network centre under qualified clinician care.
What to watch
Persistent global delay across multiple domains, adaptive skills lagging behind age expectations, and converging parental and educational concern — rather than a single IQ figure — should prompt structured developmental assessment.
Try this at home
In early childhood, use the global developmental delay descriptor until reliable standardised intellectual assessment is feasible, and document adaptive functioning across conceptual, social and practical domains, not IQ alone.
Trusted sources
Developed by SETU Consortium · Pinnacle Blooms Network · Last reviewed 2026-06-10
This is general information, not a diagnosis. A clinical AbilityScore® and any diagnosis are formed only at a Pinnacle Blooms Network centre, under qualified clinician care.
Frequently asked
What is the ICD-11 code for Intellectual Disability?
The ICD-11-MMS code is 6A00, listed as Disorders of Intellectual Development within the Neurodevelopmental Disorders grouping. Severity is specified as mild (6A00.0), moderate (6A00.1), severe (6A00.2) or profound (6A00.3).
Why does ICD-11 use the term 'Disorders of Intellectual Development'?
ICD-11 adopted this term to replace older, stigmatising nomenclature and to anchor the diagnosis in both intellectual and adaptive functioning during the developmental period, rather than IQ score alone.
How does ICD-11 handle cases where standardised testing isn't feasible?
ICD-11 provides provisional categories — such as 6A00.4, Disorder of intellectual development, provisional — so that support can begin when age or co-occurring impairment prevents valid standardised assessment.
How is severity determined under 6A00?
Severity is graded by assessing conceptual, social and practical adaptive domains alongside intellectual functioning, using appropriately normed and culturally valid instruments where available.