Child development

The CSBS DP Infant-Toddler Checklist, Explained

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Part of the Communication and Symbolic Behavior Scales Developmental Profile, the checklist scores three composites, social, speech and symbolic, against age norms, with a positive screen set at the bottom tenth percentile. Its validation ran on 5,385 children. It is the rare screening paper that names the age below which its own instrument should not be used, and this page covers what it catches, what it misses, and what comes next.

Last updated: July 2026

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What the CSBS Infant-Toddler Checklist is

The Infant-Toddler Checklist is the parent-completed screening piece of the Communication and Symbolic Behavior Scales Developmental Profile. It asks twenty-four questions about social-communication milestones, each with three to five response choices, plus one further question asking whether the parent has a concern about their child's development 1.

That last question is not decoration. A form that asks a parent what they have noticed, and then records the answer, is doing something a checklist of skills cannot do on its own.

A broadband screen looks for developmental concern in general rather than for one named condition. The checklist was validated in that role, as a general screen that also flags many children later diagnosed with autism 1.

It is one of the validated instruments named for use in primary care, and the standing rule for all of them is the same: a positive result is an indication for further evaluation, never a diagnosis 2.

What it measures before a child has words

The checklist is built around communication that predates speech. A nine-month-old or a fifteen-month-old is already communicating constantly, and the questions are about that traffic rather than about vocabulary. Those are the social-communication milestones the twenty-four items cover, which is why the instrument works at an age when a word count would tell you almost nothing 1.

Three composites are scored, alongside a total: Social, Speech and Symbolic 1. The names describe the constructs. One is about what a child does socially, one about what they produce vocally, and one about meaning, including what they do with objects and how they respond to words.

That split is the useful part. Two children can produce the same number of words and look completely different once you separate the social channel from the vocal one.

For the same period, CDC developmental milestones cover two months through five years across social and emotional, language and communication, cognitive, and movement, and name the ages at which a delay is worth raising 3. The checklist and the milestone lists are answering the same question with different instruments.

How the scoring works, and why lower is the worrying direction

The three composites are converted to standard scores with a mean of ten and a standard deviation of three, and the total is converted to a mean of one hundred with a standard deviation of fifteen. On all of them a lower score indicates greater developmental concern, which is the reverse of how most people expect a test to read 1.

A positive screen is defined as performance in the bottom tenth percentile, about 1.25 standard deviations below the mean, on the Social composite, the Symbolic composite, or the Total. The Speech composite is handled differently: a low Speech score counts only across two consecutive checklists 1.

Speech alone does not trip the screen on one form. A child has to fall in the bottom tenth percentile on Speech twice, on two consecutive checklists, for that composite to count 1.

The practical effect of that rule is that a child who is slow to produce speech while remaining on track socially and symbolically does not screen positive on the strength of a single administration. It is also the reason the raw answers cannot be turned into a result at home: converting them into composites requires the norm tables, and without those the answers are just answers.

The age below which the checklist should not be used

This is the checklist's most honest feature. Its validation screened 5,385 children between six and twenty-four months, and the authors concluded that the predictive values supported the instrument's validity from nine to twenty-four months but not at six to eight months 1. A screen run on a seven-month-old is being used outside the range its own evidence covers.

In that population sample, 56 of the 60 children later diagnosed with an autism spectrum disorder had screened positive on the checklist 1.

That is a strong result, and the four children it does not describe are the reason a negative screen is not a clearance. A screen that catches most children is not a screen that catches all of them, and no instrument in this field claims otherwise.

There is one more thing the paper does not offer. The checklist has no minimal important difference and no minimal detectable change 1. It sorts a single administration against a fixed percentile; it was not built to tell you whether a child has improved between two of them, and reading a rise in score that way is reading something the instrument does not say.

Broadband screen, autism screen: two different questions

The checklist looks for developmental concern in general; an autism-specific screen asks about autism. Both are named among the validated instruments used in primary care, and the guidance in both cases is identical: a positive result indicates further evaluation, not a diagnosis 2. The pediatric visit keeps them as separate steps for a reason.

The current autism screening schedule is standardized autism-specific screening at eighteen and twenty-four months, layered on top of developmental surveillance that continues at every visit. The same guidance holds that autism can be diagnosed as early as eighteen months 4.

Among the autism-specific instruments named for that job is the m-chat-r/f 2. Another line of work took a different shape altogether: the Q-CHAT quantitative checklist was designed to measure autistic traits on a continuum rather than to sort toddlers into two groups.

Where the Infant-Toddler Checklist fits. It can be used earlier than the autism-specific screens, which is its real advantage, and it answers a wider question, which is its real limit. A positive result says something is worth looking at. It does not say what.

What a positive checklist actually starts

A referral, and usually a fast one. For a child under three, the route runs through the state's early-intervention program under Part C of the Individuals with Disabilities Education Act, which each state administers through a designated lead agency 5. Which agency that is differs from state to state, and it is the first thing worth looking up.

Because the checklist is entirely about communication, the evaluation it most naturally leads to is a communication evaluation. A speech-language pathologist's scope of practice runs across screening, assessment and treatment of social communication in autism 6, which makes that referral a sensible next step whether or not autism turns out to be the question.

Two referrals, not one. An early-intervention referral and a diagnostic evaluation are separate errands with separate waitlists. Starting both at once costs nothing, and finishing one is not a prerequisite for beginning the other.

What to watch between the screens

Screening happens at appointments; development happens the rest of the time. The CDC milestone checklists run from two months through five years and name the ages at which a delay is worth raising, and they were revised in 2022, so an older printout on a refrigerator may not match the current ones 3.

What is worth noting down between visits:

  • Whether communication goes both ways. Not how many words, but whether sounds, looks and gestures are aimed at a person and answered.
  • Whether anything has gone backwards. A skill that was there and is now gone matters more than a skill that has not yet arrived.
  • What the child does with a new object, and whether they bring it to someone.

The early signs of autism in toddlers are described in more detail elsewhere, as are the autism signs at age two, once a child is past the checklist's upper range.

A screen is a snapshot taken at one appointment. What a parent notices across a hundred ordinary days is a different kind of evidence, and it is not the lesser one.

A concern that persists after a negative screen is still a concern, and the checklist's own extra question exists precisely because the people who wrote it knew that.

Common questions

No. It is a broadband developmental screen: it looks for concern in early social communication generally, not for autism specifically. It was validated in that role and does flag many children later diagnosed with autism, but a positive result means further evaluation is warranted. Autism-specific screening is a separate step at eighteen and twenty-four months.

Nine to twenty-four months. Its validation screened children from six months, and the authors concluded the predictive values supported validity from nine months onward but not at six to eight months. That means a checklist completed on a seven-month-old is being used outside the range its own evidence covers, which is an unusually candid thing for a test to say about itself.

Performance in the bottom tenth percentile, roughly 1.25 standard deviations below the mean, on the Social composite, the Symbolic composite, or the Total score. The Speech composite works differently: a low Speech score counts only if it appears on two consecutive checklists, so speech delay alone does not produce a positive screen from a single form.

Not into a real result. The answers have to be converted into standard scores using the instrument's norm tables before a percentile exists, and those tables are not part of the parent's copy. What a completed form can do is organise what a parent has noticed into something specific enough to hand to a clinician.

Probably not on one administration. The Speech composite only counts toward a positive screen if it falls in the bottom tenth percentile on two consecutive checklists, while the Social and Symbolic composites can each trigger a positive on their own. The design separates a child who is slow to speak from a child whose social communication is not developing.

No. In the validation sample, four of the sixty children later diagnosed with autism had screened negative. A screen sorts a population efficiently; it does not close a question about one child. A parent's persisting concern is its own reason to ask for a fuller look, and the checklist itself includes a question asking for exactly that.

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When a communication concern in a baby or toddler should not wait for the next screen

  • —Loss of babbling, gestures, or words a baby previously used: any skill that has gone backwards
  • —No back-and-forth babbling with an adult and no gestures such as reaching or showing, in a child approaching their first birthday
  • —A baby who does not turn toward a familiar voice or respond to their name, in a child whose hearing has never been formally tested
  • —A parent's concern raised at more than one visit with no screening questionnaire completed

This page explains how a screening instrument is built, scored and interpreted. It is not a screen, it produces no score, and it says nothing about any particular child. Only a clinician who has evaluated that child can do that.

References

  1. 1.Wetherby AM, Brosnan-Maddox S, Peace V, Newton L. (2008). Validation of the Infant-Toddler Checklist as a broadband screener for autism spectrum disorders from 9 to 24 months of age. Autism. doi:10.1177/1362361308094501 ✓The Infant-Toddler Checklist's structure (24 questions on social-communication milestones with 3-5 response choices each, plus one question about parental concern); its scoring (Social, Speech and Symbolic composites standard-scored to a mean of 10 and SD of 3, Total to a mean of 100 and SD of 15, with lower scores indicating greater concern); its positive-screen definition (bottom 10th percentile, 1.25 SD below the mean, on Social, Symbolic or Total, or on Speech across two consecutive checklists); the population-based validation of 5,385 children screened at 6-24 months; the conclusion that predictive values support validity from 9 to 24 months but not at 6-8 months; that 56 of 60 children later diagnosed with ASD screened positive; and that no MCID or MDC is reported.
  2. 2.Centers for Disease Control and Prevention (2024). Clinical Screening for Autism Spectrum Disorder. CDC — Autism Spectrum Disorder (ASD), Healthcare Providers. linkThat the CSBS DP Infant-Toddler Checklist and the M-CHAT-R/F are among the validated screening instruments named for use in primary care, and that a positive screen is not a diagnosis but an indication for further evaluation.
  3. 3.Centers for Disease Control and Prevention (2024). CDC's Developmental Milestones. CDC — Learn the Signs. Act Early.. linkThe CDC milestone checklists covering 2 months through 5 years across social/emotional, language/communication, cognitive and movement domains, the ages at which a delay is worth raising, and that the milestones were revised in 2022.
  4. 4.Hyman SL, Levy SE, Myers SM; AAP Council on Children With Disabilities, Section on Developmental and Behavioral Pediatrics (2020). Identification, Evaluation, and Management of Children With Autism Spectrum Disorder. Pediatrics (AAP clinical report). doi:10.1542/peds.2019-3447 ✓The recommendation of standardized autism-specific screening at 18 and 24 months alongside ongoing developmental surveillance, and that autism can be diagnosed as early as 18 months.
  5. 5.Early Childhood Technical Assistance Center (federally funded) (2024). Part C of IDEA. ECTA Center. link ✓That early intervention for children under three runs under Part C of IDEA and is administered by a state-designated lead agency that differs from state to state.
  6. 6.American Speech-Language-Hearing Association (2024). Autism (Practice Portal). ASHA Practice Portal — Clinical Topics. link ✓That a speech-language pathologist's scope of practice spans screening, assessment and treatment of social communication in autism.

6 sources, numbered by first appearance. General health information, not medical advice. AI-assisted editorial content — citations link their sources. Editorial policy

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