Autism Milestones 12-24 Months: Signs to Watch for in Toddlers
Somewhere between a first and second birthday, language and social play take center stage, and this is often when parents first start to wonder about autism. Understanding autism milestones 12-24 months can help you tell the difference between a toddler who is simply taking their time and one who might benefit from a developmental screening. This page continues our full guide to Autism Development Milestones, building on what typically happens in the first year.
This is also the window pediatricians pay the closest attention to. The American Academy of Pediatrics recommends autism-specific screening at both the 18-month and 24-month well-child visits, which makes this stage one of the most important for catching early differences.
Typical Development from 12 to 24 Months
Most toddlers move through a fairly recognizable set of changes during this year, though the pace varies from child to child.
By 15 months, most toddlers are walking independently, using at least one word beyond "mama" or "dada," pointing to show interest in something, and beginning to imitate simple actions like clapping or waving.
By 18 months, most toddlers point to objects to share interest, use six or more words, copy actions they see others do, engage in early pretend play like feeding a doll, and notice when a caregiver leaves the room.
By 24 months, most toddlers combine two words into meaningful phrases ("more juice," "go outside"), follow simple two-step directions, show interest in other children, and begin to engage in imaginative play.
Early Signs of Autism in Toddlers (12 to 24 Months)
Signs of autism in toddlers during this stage tend to cluster around language, gesture, and social play. A toddler on the spectrum might show one or more of the following patterns:
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Very few or no words by 16 months
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No meaningful two-word phrases by 24 months, not counting imitation or repetition
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Not pointing to objects to share interest, even if they can point to request something
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Little or no pretend play, such as feeding a doll or pretending to talk on the phone
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Not responding when someone points something out to them
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Limited interest in other children or in being included in play
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Repeating words or phrases without using them to communicate (echolalia)
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Unusual gait or motor patterns, such as frequent toe-walking
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A loss of words, gestures, or social skills the toddler previously had
The loss of previously acquired skills deserves particular attention at this age. Research shows that some children with autism reach milestones on a typical timeline and then plateau or regress between 18 and 24 months, which is different from a child who was simply always a little behind.
Why This Age Range Matters So Much
Autism can often be diagnosed reliably by age two by an experienced specialist, which is part of why this window carries so much weight in autism development milestones guidance. Compared to infancy, differences in social communication tend to be much easier to observe once toddlers are expected to be using words, pointing to share interest, and engaging with peers.
This is also the stage where the contrast between a shy or independent temperament and an autism-related difference becomes clearer. A toddler with a reserved personality might be quiet in new situations but will usually still enjoy sharing a discovery with a parent, pointing something out, or seeking comfort after being startled. A toddler on the spectrum is more likely to show a consistent lack of interest in sharing enjoyment or attention with others, even in familiar, comfortable settings.
What to Do If You Notice These Signs
Because autism-specific screening is already built into the 18-month and 24-month well-child visits, this is one of the more structured points to raise concerns, though you should not wait for a scheduled visit if something feels urgent sooner.
A few steps that tend to help:
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Write down specific examples, especially any change from what your toddler could do a few months earlier.
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Ask directly for the standardized autism screening tool (such as the M-CHAT) if it is not already part of the visit.
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Request a referral for a full developmental evaluation if the screening raises concerns, since a screening alone does not confirm or rule out autism.
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Keep pursuing an evaluation even if a first screening comes back reassuring, if your instincts as a parent still say something is different.
How Early Support Can Help
The 12 to 24 month window is one of the most active periods for brain development, which is a large part of why early intervention started at this age tends to show strong results in language, social skills, and adaptive behavior. Families in the Bay Area who are navigating a recent screening, diagnosis, or simply a strong instinct that something needs a closer look often start exploring in-home ABA therapy during this stage, since it can be built directly around a toddler's nap schedule and daily routine rather than requiring the family to adapt to a clinic's calendar.
Frequently Asked Questions
What are the biggest red flags for autism between 12 and 24 months? The most closely watched signs at this age include very few or no words by 16 months, no meaningful two-word phrases by 24 months, limited pointing to share interest, little pretend play, and any loss of words or social skills the toddler previously had. A loss of skills, in particular, is taken seriously by pediatricians.
Why does the AAP recommend autism screening at 18 and 24 months specifically? These ages line up with major developmental checkpoints for language, gesture, and social play, which makes differences easier to observe reliably. Screening at both points also helps catch children who develop typically at 18 months and then show a plateau or regression by 24 months.
My toddler is just shy. How is that different from autism? A shy toddler is often quiet or hesitant in new situations but will usually still want to share discoveries with a caregiver, point things out for the joy of sharing, and seek comfort when upset. A toddler on the spectrum is more likely to show a consistent lack of interest in sharing attention or enjoyment with others, even in comfortable, familiar settings, not just around strangers or new places.