Bayley-4 (Bayley Scales of Infant and Toddler Development): Scoring, Interpretation & Guide

The Bayley Scales of Infant and Toddler Development, Fourth Edition (Bayley-4) is an individually administered assessment of developmental functioning for children from 16 days to 42 months. It measures five domains: Cognitive, Language, Motor, Social-Emotional and Adaptive Behavior. Cognitive, Language and Motor are scored from play-based tasks, and the other two come from caregiver questionnaires. Composite scores have a mean of 100 and a standard deviation of 15, and subtest scaled scores have a mean of 10 and a standard deviation of 3. Administration takes 30 to 70 minutes depending on age.

This guide covers how to read Bayley-4 scores (with an interpreter below), how it differs from the Bayley-III, what can and cannot be done by telehealth, which psychometric figures are published, the Bayley-4 Screening Test, and billing basics. Facts are checked against Pearson and independent sources listed at the end.

Bayley-4 at a glance

Bayley-4 score interpreter

How to interpret Bayley-4 scores

Raw item scores are converted to scaled scores and composite scores using the age-based norm tables in the scoring manual or by Q-global, which is why a scoring calculator cannot reproduce the official conversion. Once you have the standard scores, interpretation rests on how far the child sits from the mean.

These percentiles come from the normal curve and are approximations. The manual and Q-global give the official percentile ranks and confidence intervals. A composite below 85 is more than 1 SD below the mean and a composite below 70 is more than 2 SD below the mean. Whether a given score qualifies a child for services depends on the program. For example, the Early Childhood Technical Assistance Center lists Pennsylvania's Part C definition as a 25% delay or 1.5 SD below the mean in one area, and other states differ, so check your state's definition.

Two further points help avoid over-reading a score. First, the Bayley-4 compares a child's performance with same-age peers using standard scores and is not an IQ test. Second, a single score is a snapshot, so combine it with caregiver report, observation and the child's history.

Bayley-III versus Bayley-4: what changed

Pearson sources for this table: Bayley-III to Bayley-4 comparison, What changed and the Bayley-4 technical report. Bayley-III and Bayley-4 scores are not interchangeable, so note the edition on every report and take care when comparing a child's scores across editions. For history, the original scales were published in 1969 and updated in 1993, 2006 and 2019 (ScienceDirect overview).

The five Bayley-4 domains

Physical therapists often focus on the Motor scale, and speech-language pathologists on Language. Pair the Bayley-4 with other measures from our PROMs and functional outcomes library when you need a fuller picture of function.

Bayley-4 psychometric properties

The figures come from the Shirley Ryan AbilityLab Rehabilitation Measures database and the Pearson technical report. The norm sample was drawn in the United States, so check how well it fits children from other populations.

The Bayley-4 Screening Test

Pearson sells a companion Screening Test for children from 16 days to 42 months. It takes 15 to 25 minutes, screens Cognitive, Language and Motor, and uses cut-scores by age (see Pearson's screener flyer). It flags children who may need a full evaluation. It is not a diagnostic tool, so a result near the cut-score should lead to the full Bayley-4 or another comprehensive assessment.

Bayley-4 and telehealth

See Pearson's telepractice guidance for the Bayley-4. In hybrid models, record which parts were done in person and which by caregiver report.

Bayley-4 billing basics

Developmental testing is usually reported with CPT 96112 for the first hour of test administration, with interpretation and report, and add-on CPT 96113 for each additional 30 minutes. Which clinicians may bill them, and whether prior authorization is required, depends on the payer, the state and the clinician's license, so confirm each payer's policy in writing. Early intervention evaluations may be paid through the state program instead of insurance. Document the date, total administration time, domains tested, scores and interpretation. For code details see our CPT code library and physical therapy CPT codes reference sheet, and for fewer rejections read about reducing claim denials and prior authorization.

Special considerations

Prematurity and corrected age

Corrected age matters for children born early. Pearson's Bayley-III guidance supports adjusting up to 24 months, because the majority of children catch up by then (Pearson Bayley FAQ). The Bayley-4 on Q-global adjusts the start point from the estimated due date. For the exact Bayley-4 correction rules, follow the Bayley-4 manual.

Re-administration

Pearson's Bayley-III guidance recommends an interval of about 3 months for children under 12 months and about 6 months for older children. Check the Bayley-4 manual for its own recommendation and avoid retesting sooner when practice effects are a risk.

Children with motor or sensory impairments

Interpret scores with care when a child's impairment limits response to the standard tasks, and describe any modifications in the report. Add clinical observation and other measures rather than relying on the score alone.

Prevalence context

The CDC reports that about 1 in 6, or about 17%, of children aged 3 through 17 years have one or more developmental disabilities (CDC). That is why timely screening and referral matter.

Strengths and limitations

• Strengths: five domains in one tool, published reliability and validity data, polytomous item scoring, digital scoring on Q-global and a companion screener.
• Limitations: it takes 30 to 70 minutes, needs trained examiners, offers a snapshot rather than continuous monitoring, uses a US norm sample, and cannot be done by telepractice for Cognitive, Language and Motor. At Pearson's listed prices, the print complete kit is $1,563.50 and the print screening combo kit is $1,769.20, so check current prices.

Tips for families before a Bayley assessment

1. Schedule at the right time. Choose a time when your child is usually alert.
2. Meet basic needs. Make sure your child is rested and fed.
3. Bring comfort items. A familiar toy or blanket helps.
4. Stay calm. Children often pick up on a parent's stress.
5. Ask questions. Ask the examiner what each score means and what happens next.

Frequently asked questions

What does the Bayley-4 measure?

It measures developmental functioning in five domains: Cognitive, Language, Motor, Social-Emotional and Adaptive Behavior, for children from 16 days to 42 months.

What Bayley-4 score indicates a developmental delay?

There is no single cutoff. A composite below 85 is more than 1 SD below the mean, and below 70 is more than 2 SD below. Programs set their own rules, for example 1.5 SD or a percent delay in one area, so confirm the definition that applies to your state or payer.

How do I interpret Bayley-4 scaled scores?

Scaled scores have a mean of 10 and an SD of 3. A scaled score of 7 is 1 SD below the mean and 4 is 2 SD below. Use the interpreter above for the SD distance and approximate percentile.

How do I convert raw scores to scaled scores?

Use the age-based norm tables in the Bayley-4 scoring manual or score the assessment in Q-global. The tables are Pearson's copyrighted material, so this page does not reproduce them.

Is there a free Bayley-4 scoring manual PDF?

The manual is a Pearson product, sold with the kit and used with Q-global. Buy it from Pearson or use your employer's licensed copy rather than an unofficial download.

What is the difference between the Bayley-III and the Bayley-4?

The Bayley-4 uses 2, 1, 0 item scoring, takes 30 to 70 minutes instead of 30 to 90, draws Adaptive Behavior items from the Vineland-3 and offers Q-global delivery. Scores are not interchangeable between editions.

Can the Bayley-4 be given by telehealth?

The Social-Emotional and Adaptive Behavior questionnaires can be completed remotely through Q-global. The Cognitive, Language and Motor scales were not standardized for telepractice.

Who can administer the Bayley-4?

Pearson lists qualification level B, and the Rehabilitation Measures database describes a master's or doctoral degree with appropriate training. Check Pearson's qualification rules for your credential, and your state license and payer rules.

How long does the Bayley-4 take?

Pearson lists 30 to 70 minutes depending on the child's age. The Screening Test takes 15 to 25 minutes.

How often can the Bayley-4 be repeated?

Pearson's Bayley-III guidance suggests about 3 months for children under 12 months and about 6 months for older children. Check the Bayley-4 manual for its guidance.

Is the Bayley-4 an IQ test?

No. It compares a child's developmental performance with same-age peers using standard scores and does not produce an IQ.

What CPT codes are used for the Bayley-4?

Developmental testing is commonly reported with CPT 96112 (first hour) and 96113 (each additional 30 minutes). Whether a payer accepts them from your discipline varies.

Sources and further reading

• Pearson: Bayley-4 product page
• Pearson: Bayley-4 technical report
• Pearson: Bayley-III to Bayley-4 comparison
• Pearson: Bayley-III to Bayley-4 what changed
• Pearson: Bayley-4 Screening Test flyer
• Pearson: Telepractice and the Bayley-4
• Pearson: Bayley-III FAQ on corrected age and re-administration
• Shirley Ryan AbilityLab: Bayley-4 in the Rehabilitation Measures database
• ScienceDirect: Bayley Scales of Infant Development overview
• CDC: Developmental disabilities in children
• ECTA Center: state Part C eligibility definitions

Score and track this measure in your EMR and see it across your caseload with reporting and analytics. This article is informational and does not constitute medical advice. The Bayley-4 should only be administered and interpreted by qualified professionals.