Bayley Scales of Infant and Toddler Development | Third Edition

Bayley Scales of Infant and Toddler Development® | Third Edition (Bayley®-III), is a comprehensive tool to identify development issues during early childhood. The Bayley-4 is now available!

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  • Test forms & reports

    Booklets, record forms, answer sheets, report usages & subscriptions

    6 options

    from $108.90
  • Support materials

    Manuals, stimulus books, replacement items & other materials

    35 options

    from $1.60
  • All products

    All tests & materials offered for Bayley-III

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  • Bayley-III Administration Manual (Print)
    0158027280 Qualification Level B


  • Bayley-III Technical Manual (Print)
    0158027299 Qualification Level B


  • Bayley-III Picture Book (Print)
    0158027345 Qualification Level B


  • Bayley-III Stimulus Book (Print)
    0158027337 Qualification Level B


  • Bayley-III Enhanced Administration/Scoring DVD Qty 4
    0158027612 Qualification Level B

    Includes item-by-item review of administration and scoring for the Bayley-III across 4 DVDs


  • Bayley-III Fundamental Administration DVD
    0158027833 Qualification Level B

    Includes essentials for Bayley-III administration; see also enhanced training DVD


  • Bayley-III Observational Checklist Qty 1 (Print)
    0154027014 Qualification Level B

    Includes laminated form for re-use


  • Bayley-III Social-Emotional and Adaptive Behavior Questionnaires Qty 25 (Print)
    0158027566 Qualification Level B


  • Bayley-III Cognitive Language Motor Record Forms Qty 25 (Print)
    0158027302 Qualification Level B


  • Bayley-III Cognitive Record Forms Qty 25 (Print)
    0158027647 Qualification Level B


  • Bayley-III Language Record Forms Qty 25 (Print)
    0158027655 Qualification Level B


  • Bayley-III Motor Record Forms Qty 25 (Print)
    0158027310 Qualification Level B


  • Bayley-III Caregiver Report Forms Qty 25 (Print)
    0158027574 Qualification Level B


  • Bayley-4/III Red Blocks Qty 3
    0154027588 Qualification Level B


  • Bayley-III Ducks Set Qty 7
    0154027634 Qualification Level B


  • Bayley-4/III Red Blocks with Hole Qty 4
    0154027618 Qualification Level B


  • Bayley-II/III Clear Box
    0154028169 Qualification Level B

    Includes a box that has an opening on one end


  • Crayon Red 4 Inch Large Qty 1
    0154028428 Qualification Level B

    This item is part of Bayley-III/4 and BINS assessments


  • Bayley-4/III Doll
    015402855X Qualification Level B


  • Spoon Metal Round 6 Inches
    0154028797 Qualification Level C

    Included in Bayley-III/-4, BINS, and PLS-5 assessments


  • Bayley-4/III Ball 4 Inch
    0154027308 Qualification Level B


  • Coin Bank
    0154027316 Qualification Level B

    Included in the Bayley-III and M-FUN assessments


  • Bayley-4/III Blocks Qty 6
    0154027340 Qualification Level B

    Includes 4 small blocks; 2 medium blocks


  • Bayley-III Bottle with Lid 33mm
    0154027359 Qualification Level B


  • Bayley-III Glitter Bracelet
    0154027367 Qualification Level B


  • Bayley-III Lacing Card
    0154027375 Qualification Level B


  • Bayley-III Memory Cards Qty 6
    0154027383 Qualification Level B

    Includes 3 pairs of cards


  • Bayley-4/III Mirror 5X7
    0154027391 Qualification Level B


  • Bayley-4/III Oval Shoe Lace
    0154027405 Qualification Level B


  • Wash Cloth Yellow
    0158896734 Qualification Level B

    Included in Bayley, M-FUN, PLS, and Mullen assessments


  • Bayley-III Puzzles Qty 3
    015402743X Qualification Level B


  • PLS-5 Plastic Glass Clear
    0158896793 Qualification Level B


  • Bayley-III Drawstring Bag Small
    0154027456 Qualification Level B


  • Bayley-III Stepping Path
    0154027472 Qualification Level B


  • Bayley-4/III Storybook
    0154027480 Qualification Level B


  • Rattle Pink
    0154027510 Qualification Level B

    Included in the Bayley-III/-4 and PLS-5 assessments


  • Pencil Primary Sharpened No Eraser
    0158000064 Qualification Level A

    Included in the Bayley-III/-4 and DAS-II assessments


  • Duck Yellow Squeaky Toy
    0154027219 Qualification Level B

    Includes a 3.5 inch duck used in the Bayley-III, Bayley-4, and PLS-5 assessments


  • Car Green Qty 1
    0158180933 Qualification Level B

    This item is part of Bayley-III and DAS-II assessments


  • PLS-5 Teddy Bear Plastic Purple
    0158659082 Qualification Level B


  • Bayley-III Cubes Red Qty 8
    0154027626 Qualification Level B



Publication date:
Age range:
1 to 42 months
Index scores and Subtest Scaled scores
Qualification level:
Completion time:
30 to 90 minutes (depending upon age of child)

Product Details

The Bayley-4 is now available!

Bayley-III uses caregiver or parent involvement to optimize input from the child’s natural environment.


  • Identify infant and toddler strengths and competencies, as well as their weaknesses.
  • Get normative information consistent with developmental domains identified by current IDEA early childhood legislation.
  • Determine the need for further in-depth assessment.
  • Administer one or more domain subtests individually.
  • Use growth scores to chart intervention progress.


Bayley-III combines superior psychometric standards with two additional scales and more clinically useful features.

  • A core battery of five scales.
  • Playful, engaging toys and activities.
  • Excellent validity and reliability.
  • Scores: standard scores, age equivalents, percentiles, with cut scores and T scores.
  • Optional training materials.


View list of scales


Sample Reports




Frequently asked questions follow. Click on a question to see the response.

Test Content

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).


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 standardized 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?

The item in question is "Uses pencil to obtain object." The examiner should position him- or herself alongside the child, to give the child the proper perspective. In all instances, the directions in the Administration Manual should be followed.

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 minimizes 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 recognize 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 familiarize the child with tasks and encourage vocalizations.

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.

How soon can the Bayley–III be readministered 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 readministered 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.

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.

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.

What was the rationale for adjusting 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 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.

For children ages 2:6–3:6, both the Bayley–III and the Wechsler Preschool and Primary Scale of Intelligence—Third Edition (WPPSI–III; Wechsler, 2002) could be administered. Which instrument should be used for this age range?

Which test to use depends on your clinical judgment and the purpose of testing. Practitioners can use either or both instruments for children ages 30–42 months (2 years 6 months and 3 years 6 months). Though both measures provide an estimate of a child’s cognitive functioning, the instruments are designed for different purposes. The Bayley–III provides information about whether a child’s developmental trajectory in the cognitive domain is proceeding as expected, relative to same-age peers. It also provides this type of information for language, motor, social-emotional, and adaptive behavior domains. The WPPSI–III is specifically designed to measure a child’s overall cognitive ability, as well as his or her cognitive ability in more specific domains (e.g., verbal, perceptual, processing speed). The Bayley–III should be used to evaluate cognitive ability in low-functioning children in this age range because it provides an extended floor. The WPPSI–III should be used to evaluate cognitive ability in high-functioning children in this age range, because it provides an extended ceiling. If results of the Bayley–III suggest delays in the cognitive domain, the WPPSI–III may provide additional information on the specific areas of cognitive ability that are problematic for the child. If an ability score (e.g., FSIQ) is required, the WPPSI–III should be used.


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. U.S. federal mandates, such as IDEIA, emphasize 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.

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 is the difference between a score of 0 (can’t tell) and 1 (none of the time) 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 behaviors.

Multi-Disciplinary Evaluation

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.



The following training events are available for Bayley-III.


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