Autism falls under the category of neurodevelopmental disorders in both major diagnostic systems used worldwide. In the United States, the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) classifies it as autism spectrum disorder, or ASD. The World Health Organization’s International Classification of Diseases (ICD-11) uses the same name and places it in the same neurodevelopmental grouping. But depending on the context, autism also shows up under different labels in education law, disability frameworks, and newer paradigms like neurodiversity.
The Neurodevelopmental Disorders Category
Neurodevelopmental disorders are conditions rooted in how the brain develops, typically showing up in early childhood. Autism shares this category with several other conditions: ADHD, intellectual disability, communication disorders (like speech sound disorder and stuttering), specific learning disorders, and motor disorders including tic disorders and Tourette’s. What ties them together is that they all involve differences in brain development that affect how a person functions in daily life.
Within this group, autism is defined by two core features. The first is persistent differences in social communication and interaction, covering everything from back-and-forth conversation to reading body language to building and maintaining relationships. The second is restricted, repetitive patterns of behavior or interests. This can look like repeating certain movements, insisting on sameness in routines, developing intensely focused interests, or being unusually sensitive (or unusually under-responsive) to sensory input like sounds, textures, or lights. A person needs to show all three types of social communication differences plus at least two of the four repetitive behavior patterns to meet the diagnostic criteria.
How the Category Changed in 2013
Before the DSM-5 was published in 2013, autism wasn’t a single diagnosis. The previous edition split it into four separate conditions: autistic disorder, Asperger’s disorder, childhood disintegrative disorder, and pervasive developmental disorder not otherwise specified (PDD-NOS). The American Psychiatric Association merged all four into one umbrella diagnosis, autism spectrum disorder, based on scientific consensus that these were different presentations of the same condition rather than truly distinct disorders.
This is why you’ll still hear people refer to “Asperger’s” even though it’s no longer a standalone diagnosis. Someone who would have received an Asperger’s diagnosis before 2013 would now be diagnosed with autism spectrum disorder, likely at Level 1 support needs.
The Three Support Levels
Because autism spans such a wide range of experiences, the DSM-5 includes three levels that describe how much support a person needs in daily life:
- Level 1: Requiring support. A person at this level can generally function independently but struggles in certain social situations or with flexibility.
- Level 2: Requiring substantial support. Social communication difficulties are more noticeable, and repetitive behaviors or rigidity around routines significantly affect daily functioning.
- Level 3: Requiring very substantial support. A person at this level has severe challenges with communication and daily living that require extensive help.
These levels aren’t fixed for life. Someone’s support needs can shift depending on their environment, stress levels, and the accommodations available to them. The levels also don’t capture every dimension of a person’s experience, which is one reason many autistic people and clinicians find them incomplete.
Autism as a Disability Category in Schools
In U.S. education, autism has its own separate category under the Individuals with Disabilities Education Act (IDEA). The law defines it as “a developmental disability significantly affecting verbal and nonverbal communication and social interaction, generally evident before age three, that adversely affects a child’s educational performance.” This definition also notes characteristics like repetitive activities, resistance to changes in routine, and unusual responses to sensory experiences.
One important detail: a child who first shows characteristics of autism after age three can still qualify under this category. The law also specifies that autism doesn’t apply if a child’s educational challenges are primarily caused by an emotional disturbance. This matters because the IDEA category determines what kind of special education services and supports a child can access in public schools.
The Medical Model vs. the Neurodiversity Framework
The clinical classification of autism as a “disorder” reflects what’s known as the medical model, which treats autism as a deficit located within the individual. Under this lens, differences in social communication, repetitive behaviors, and sensory processing are framed as impairments that need intervention.
The neurodiversity framework offers a different perspective. It views autism as a natural variation in how human brains develop, not a disease to be corrected. There is no singular “healthy” brain under this model, and the goal shifts from changing autistic individuals to fit societal norms toward changing environments to accommodate different neurological profiles. If a grocery store is overwhelming for an autistic person, the neurodiversity lens asks what’s wrong with the store’s design rather than what’s wrong with the person.
The social model of disability takes a similar approach, arguing that disability is created by environments and systems that fail to account for human diversity. Under this view, autism is still a disability, but the disabling factor is the mismatch between an autistic person’s needs and the world around them, not the autism itself. These frameworks increasingly shape policy discussions, workplace accommodations, and how autistic people understand their own identities, even as the clinical classifications remain rooted in the medical model.
How Common Autism Is Today
The most recent CDC data, published in April 2025 and based on surveillance from 2022, found that about 1 in 31 eight-year-olds across 16 U.S. sites had been identified with autism. Among four-year-olds, the rate was roughly 1 in 34. These numbers have risen steadily over the past two decades, driven largely by broader diagnostic criteria, better screening, and increased awareness rather than a true surge in the underlying condition. The full range of intellectual ability and language skills is represented across the spectrum: some autistic people have significant intellectual disabilities, while others have average or above-average cognitive abilities.