Bayley Scales of Infant and Toddler Development, Third Edition

Bayley Scales of Infant and Toddler Development, Third Edition (Bayley-III)  examines all the facets of a young child's development. Children are assessed in the five key developmental domains of cognition, language, social-emotional, motor and adaptive behaviour.

Bayley-4 UK is now available to order. Learn More 
IMPORTANT: Bayley-III Complete Kit is no longer available for purchase
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Bayley-III Manipulative Screener Set 1
9780158027357 Qualification Level B

Includes Bayley-II Set Of 2 Crayons (Group H), Bayley-II Bell (Group G), Bayley-III Spoon, Bayley-III Plastic Glass Clear, Bayley-III Bottle With Lid 33Mm, Bayley-III Oval Shoe Lace, Bayley-III Squeeze Toy, Bayley-III Ziplock Bag 12 X 5, Bayley-II Clr Box-Open End (Group E), Bayley-II Doll (Grp H), Bayley-II Rattle (Grp H), Bayley-II Ring W/ String (Grp I)



Estimated to ship:More than 12 weeks


Publication date:
Age range:
1 month to 42 months
Qualification level:

Product Details

Bayley-4 UK is now available to order. Learn More

The Bayley Scales of Infant Development (Bayley-III) are recognised internationally as one of the most comprehensive tools to assess children from as young as one month old. Bayley-III identifies infant and toddler strengths and competencies, as well as their weakness. It also provides a valid and reliable measure of a child's abilities, in addition to giving comparison data for children with high-incidence clinical diagnoses. Growth scores can be used to chart intervention progress, and it's useful in programme evaluation, ongoing monitoring of progress and outcome measurement.


  • Obtain detailed information even from non-verbal children as to their functioning
  • Children are assessed in the five key developmental domains of cognition, language, social-emotional, motor and adaptive behaviour.
  • Easier to administer, more user-friendly; easy-to-follow record forms, easel-back stimulus book, child-appealing manipulatives and play-based items to facilitate assessment
  • Easier to determine if child performed the target behaviour
  • Simplified scoring rules
  • Extended floor and ceiling - Clinician can more easily identify lower functioning infants and toddlers
  • Improved clinical studies - Special data collected and presented on children with high-incidence clinical diagnoses
  • More parent/caregiver involvement - New test items allow for family input
  • Reduced kit weight and size


  • Core battery of five scales: Three scales administered with child interaction; cognitive, motor, language. Two scales conducted with parent questionnaires: social-emotional, adaptive behaviour
  • Caregiver Report Form - a template for the examiner to provide scores, information on tests given, how child performed and recommendations
  • Behaviour Observation Inventory - separate scale for validating examiner and parent perceptions of the child's responses
  • New norms based on 1,700 children stratified according age, based on the 2000 US Census
  • Ideal for team-testing or multi-disciplinary teams where a professional in each area may assess the child
  • Flexible - can administer one or more domain subtests individually
  • Rolling case for ease of travel
  • Social-emotional subtest - Authored by one of the USA's leading experts in child development, Stanley Greenspan
  • Adaptive Behaviour subtest - Written by ABAS-II authors Patti L Harrison and Thomas Oakland
  • Caregiver Report
  • Growth Scores and Growth Charts
  • Screening Test - A true screener to determine if further testing is necessary

Bayley-III UK Validation

Now available, the Bayley-III UK and Ireland Supplement reports the results of the UK and Ireland validation study, general considerations for use of the Bayley lll in the UK and Ireland, and 8 case studies.

A broadly representative sample of 221 children aged around 12 and 24 months in the UK and Ireland was included, taking into account geographic region, gender, age, ethnicity and parental education.

The case studies present developmental history, assessment information, and interpretation of scores for eight children with one of the following conditions: birth asphyxia, prenatal exposure to substance abuse, seizures, speech and language difficulties, Cerebral Palsy, Down Syndrome or PDD.

The EPICure Study is using Bayley-III - click EPICure Study for more information.

IMPORTANT: Bayley-III Complete Kit is no longer available for purchase




Can all items that use the same materials within an age group be administered one after the other (e.g., all items that use blocks), similar to the BSID–II administration format?

Because the items are ordered by difficulty, administer the items in each subtest in the order listed (with the exception of series items). The subtests were standardised by having examiners follow the item order provided. It also ensures that all pertinent items are administered (none are forgotten), and that reversal and discontinue rules are met quickly, with no extraneous items that may contribute to the fatigue of the child.

There is an item on the Bayley–III video that shows the examiner positioned across from the child, when the Administration Manual indicates that for the item, the examiner should be positioned next to the child. Which directions should I follow?

Yes, new clinical data has been collected with people with a range of clinical difficulties. This data is included in the new manual.

Why is it recommended to administer the Receptive Communication subtest prior to the Expressive Communication subtest?

Statistically, we did not find practice effects based on subtest order for any subtests. The number of items that can be scored through observation of the child also minimises the likelihood of practice effects with the Communication subtests.

However, there are some reasons for recommending that Receptive Communication be administered prior to Expressive Communication. Some stimulus items are similar across content and repeated exposure to these pictures may make it easier for the child to recognise them in the Receptive Communication subtest.

In addition, many young children must establish rapport with the examiner before expressing themselves vocally by naming objects or speaking to the examiner; the Receptive items can help familiarise the child with tasks and encourage vocalisations.

Can an examiner accept baby signs/ASL as words on the Expressive Communication Scale?

Many of the Expressive Communication items indicate that approximations (the implication being verbal approximations) can be accepted. If the child is capable of speaking, the child should be prompted to use spoken words rather than signs. If, however, the child is signing as an accommodation, then the clinician would need to take that into account when interpreting the results.

What start point should an examiner use when testing a child with suspected deficits?

The start points were chosen to accommodate most children with some degree of delay. If the examiner suspects sufficient delays such that the child will likely reverse, the examiner can begin one start point below the age-appropriate start point, and reverse as needed. It is not recommended that the examiner begin administration any earlier, in order to eliminate the possibility of multiple basals.

Can children be administered the Bayley–III in the home setting?

The Bayley-III CAN be administered in the home, but the examiner must maintain standard procedures and keep distractions to a minimum.

There are a number of items that can be considered sequential that either are not marked as sequential, or are only partially noted as sequential (i.e., later items in the “sequence” not listed). Why aren’t these noted as series items?

Items are marked as series items only if the administration is exactly the same for each item in the series. That is why the Rotated Pink Board is not identified as part of the Pink Board Series.

Scores and Scoring

Will there be Cognitive-Language Composite score similar to the BSID–II MDI? Is there an overall score available?

At this point, there are no plans to develop either a Bayley-III Cognitive-Language composite score that corresponds with the BSID-II MDI or an overall composite. The reasoning behind separating the scores is because at this young age it is important to distinguish between delays related to language difficulty and those related to cognitive difficulty.

US federal mandates, such as IDEIA, emphasise the need to provide scores for the individual domains, rather than a global composite score. A composite score can also mask delays if one area is strong while the other is weak.

If the Social-Emotional Scale on the Bayley–III is the same as the Greenspan Social-Emotional Growth Chart, why are there different scores available for the two instruments?

The difference between the Greenspan Social-Emotional Growth Chart and the Bayley–III Social-Emotional Scale is that the Greenspan Social-Emotional Growth Chart provides only cut scores; the Bayley-III provides scaled scores for this measure.

What is the difference between a score of 0 (can’t tell) and 1 (don’t know) for the Social-Emotional Scale?

The score of 0 should be chosen if the respondent doesn't feel he/she knows the child well enough to respond with confidence (lack of familiarity with the child or limited settings in which the respondent has observed the child). The score of 1 should be chosen if the respondent is familiar enough with the child to know that the child never exhibits those behaviours.

What was the rationale for adjusting to prematurity up to 24 months?

It was a combination of evidence from the literature and recommendations from the Bayley–III advisory panel. Discussions for adjusting to prematurity to 24 months of age began early in the development process of the Bayley–III and follows the same recommendations made for the BSID–II. The adjustment for prematurity was not taken beyond 24 months because the advisory panel and the literature indicate the vast majority of children "catch up" by 24 months of age.

Can the Bayley–III Scoring Assistant® software be used without the PDA administration?

Administration of the Bayley–III using the PDA is not necessary in order to use the Scoring Assistant (although they are packaged together). Users can enter raw scores into the Scoring Assistant to obtain the tables and graphs report.

Test-retest time

How soon can the Bayley–III be re-administered in order to measure growth?

The types of items administered to infants are unlikely to be "learned" or to produce practice effects, so children can be re-administered the Bayley–III in a shorter time frame. An interval of approximately 3 months is recommended for children under 12 months of age; an interval of approximately 6 months is recommended for children older than 12 months, although shorter intervals can be used if warranted.


Is the Language Scale sufficiently comprehensive so that additional language assessment is not necessary, especially for the younger children?

The Language Scale is sufficient for determining if a language problem exists. It may also indicate what language problem it is likely to be. However, in order to pinpoint the problem to determine appropriate intervention (particularly if referring to a Speech Language Pathologist), additional assessment will be necessary. The Preschool Language Scale—Fourth Edition is one instrument that can be given if the Bayley–III Language Scale indicates delays.

Why are there separate Record Forms for each of the Cognitive, Language, and Motor Scales? Are they different from what is contained in the comprehensive Record Form?

A separate Record Form is available for each Scale in order to provide flexibility for customer needs. For instance, these record forms can provide more efficiency when conducting research, and for multidisciplinary and arena assessment teams. The standard Record Form (combining all 3 Scales) contains all the information and items found in the individual Record Forms

How much overlap is there between the Preschool Language Scale—Fourth Edition and the Bayley–III Language Scale?

There are only 44 items in the Bayley–III Language Scale that originated from the PLS-4. A validity study between the PLS–4 and the Bayley–III indicate no practice effects between the two tests, so administration of one test does not affect performance on the other test.

Where can I find additional interpretive guidelines for the Social-Emotional Scale?

For additional interpretive guidelines specific to the social-emotional score, Dr Greenspan includes some "next steps" within the manual for the Greenspan Social-Emotional Growth Chart. The material is adapted from what is found in books authored by Dr Greenspan (including Building Healthy Minds and The Functional Emotional Assessment Scale for Infancy and Early Childhood).

How can I fit the Bayley-III kit in the rolling bag?

The best solution is to remove the fabric pocket organiser in the main compartment to create more storage space. The organiser unsnaps easily at the back of the compartment. Here are some options for storing the kit components:

1. The stimulus book and manuals could fit in the inner pockets on the inside flap of the main compartment.

2. Manipulatives will fit in the main compartment.

3. The record forms and possibly a manual could fit on the outside flap.

4. Small pockets on the inside and outside of the flap are big enough for pencils, stop watch and a pocket calculator.

5. Pockets on each side and on the back of the case provide additional storage space.