Bayley Scales of Infant and Toddler Development – Third Edition (Bayley III)

Bayley Scales of Infant and Toddler Development – Third Edition (Bayley III)


Examine 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

Examine 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


Nancy Bayley, PhD


Examine all the facets of a young child’s development

Age Range:

1 month to 42 months


Individual – 30 to 90 minutes

Completion Time:

30 to 90 minutes (depending upon age of child)




Index scores and Subtest Scaled scores

Publication Date:


What we do today makes all the difference tomorrow.

Every child deserves to make his mark. Each should have every opportunity to reach his full potential. And you can help make that possible. With Bayley–III, you have the comprehensive tool you need to identify issues early on. To address early childhood situations before they become lifelong problems. And to give every child a chance to succeed. With Bayley–III, you have the power to make a positive impact, early and often.

This is your one stop location for information on the Bayley Scales of Infant and Toddler Development – Third Edition.

What’s new about Bayley-III?

Long known as the premier assessment for measuring developmental delays in the very young, this newest edition – the Bayley Scales of Infant and Toddler Development – Third Edition (Bayley–III) – combines the superior psychometric standards you expect with two additional scales and more clinically useful features than ever.

Plus . . . as a Bayley-III customer, you get unparalleled service and support from a highly credentialed sales team.

Bayley-III complete kit Rolling case now standard!


  • Social-Emotional subtest
    Authored by one of the nation’s leading experts in child development, Stanley Greenspan, M.D.
  • Adaptive Behavior subtest
    Written by ABAS®-II authors Patti L. Harrison, Ph.D. and Thomas Oakland, Ph.D.
  • Screening Test
    A true screener to determine if further testing is indicated.
  • Caregiver Report
    With suggestions to help parents plan for their child.
  • Scoring Assistant
    For cognitive, language, and motor scales, adding ease and efficiency, ideal for team and arena testing.
  • Growth Scores and Growth Charts
    Chart a child’s growth over time.


  • 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.
  • Extended floor and ceiling. Clinician can more easily identify lower and higher functioning infants and toddlers.
  • Improved clinical studies. Special data collected and presented on children with high-incidence clinical diagnoses.
  • New norms. Current normative sample representing 1,700 children stratified according to age, based on the 2000 U.S. Census.
  • Simplified scoring rules. It’s easier to determine if child performs target behavior.
  • More parent/caregiver involvement. New test items allow for family input.

Helping children make a distinct mark through better assessment in all five IDEA areas.

Even when a child can’t speak, he can tell us something. How he feels. How he thinks. How he interacts with the world around him. And we need to know how to read the signs. With Bayley-III, you can. You have a comprehensive tool for identifying, measuring, and assessing a child’s development.

For over 20 years, professionals working with infants and toddlers have relied on the proven Bayley Scales of Infant Development. And today, they have even greater reason to do so. With the new Bayley–III, professionals have the most comprehensive assessment tool for determining developmental delays in children one month to 42 months old.

Bayley-III Complete Test

Easy to Use.
Hard to argue with.

Unlike other solutions that have manipulatives that can be cumbersome or time consuming, Bayley–III is easy to use and to transport. It’s also very easy to administer, and the results are exceedingly reliable. It is administered using a caregiver’s or parent’s involvement, allowing more input to be gathered from the child’s natural environment. Additionally, all assessment factors are based on the age of the child, allowing for more accurate developmental assessments.

New Design!

Rolling case for easier portability

Who can use Bayley–III?
You can.

You must have the ability, not just to administer the test, but to analyze and interpret the results. Qualified personnel will likely have training in the following areas:

  • formal training in the use, administration and interpretation of standardized assessment tools and psychometrics
  • supervised mental health and/or educational training specific to working with parents and assessing young children
  • supervised training in infant and child development

Sample qualified personnel: psychologists, psychiatrists, speech and language therapists, occupational and physical therapists specializing in early intervention, early interventionists, social workers, developmental pediatricians, pediatric nurse practitioners. Those who qualify will most likely have at least a Master’s degree.

If you are an appropriately trained, experienced practitioner in these areas, you can benefit from using Bayley–III.

  • Early intervention specialist
  • Early childhood specialist
  • Childhood development specialist
  • Cross-disciplinary professional
  • School psychologist
  • Assessment specialist

Features & Benefits

  • Core battery of five scales.
    • Three scales administered with child interaction – cognitive, motor, language.
    • Two scales conducted with parent questionnaires – social-emotional, adaptive behavior.
  • Ideal for team-testing or multi-disciplinary teams where a professional in each area may assess the child (psychologist, SLP, OT/PT).
  • Caregiver Report Form – a template for the examiner to provide scores, information on tests given, how the childperformed and recommendations.
  • Behavior Observation Inventory – separate scale for validating examiner and parent perceptions of the child’s responses.
  • Extensive clinical studies – including premature, small for gestational age, Downs syndrome, pervasive developmental disorder, at-risk, FAS/poly substance use, asphyxia, cerebral palsy and language impairment.
  • Extensive validity studies –
    • Bayley Scales of Infant Development – Second Edition.
    • Preschool Language Scale – Fourth Edition.
    • Adaptive Behavior Assessment System®– Second Edition.
    • Wechsler Preschool and Primary Scale of Intelligence™ – Third Edition.
    • Infant-Toddler Social Emotional Assessment.
    • Peabody Developmental Motor Scales – Second Edition.
  • Reduced kit weight and size.
  • Simplified scoring rules.
  • Rolling case portability for easier travel.
  • Easier to determine if child performed the target behavior.

Main Features:

  • Playful, engaging toys and activities
  • Excellent validity and reliability
  • Scores provided: standard scores, age equivalents, percentiles, with cut scores and T scores.
  • Optional training materials available
  • Scoring Assistant – optional


  • Ideal for use when you suspect delays or problems in early development
  • Determines the need for further in-depth assessment
  • Indicates strengths, weaknesses, and competencies so that parents and professionals can properly plan for the child
  • Aligns with IDEA requirements for support and intervention
  • Excellent for use in cross-disciplinary teams
  • Allows for more caregiver involvement in test items

Helping you link assessment with intervention.

  • Identifies infant and toddler strengths and competencies, as well as their weaknesses.
  • Provides normative information consistent with developmental domains identified by current IDEA early childhood legislation.
  • Valid and reliable measure of a child’s abilities.
  • Comparison data for children with high-incidence clinical diagnoses.
  • Flexible – can administer one or more domain subtests individually.
  • Growth scores can be used to chart intervention progress.

Areas of Assessment

Bayley-III: The Definitive Solution

The definitive solution for measuring the complete child.






Bayley-III Developmental Domains

Five Developmental Domains

Table of Contents of Developmental Domains

Adaptive Behavior
Authored by ABAS®-II authors Patti L. Harrison, Ph.D. and Thomas Oakland, Ph.D.

  • Communication
  • Community use
  • Functional pre-academics
  • Home living
  • Health and safety
  • Leisure
  • Self-care
  • Self-direction
  • Social
  • Motor


  • Sensorimotor development
  • Exploration and manipulation
  • Object relatedness
  • Concept formation
  • Memory
  • Habituation
  • Visual acuity
  • Visual preference
  • Object permanence
  • Plus other aspects of cognitive processing

Items measure age-appropriate skills including:

  • Counting (with one-to-one correspondence and cardinality)
  • Visual and tactile exploration
  • Object assembly
  • Puzzle board completion
  • Matching colors
  • Comparing masses
  • Representational and pretend play
  • Discriminating patterns


Expressive communication
Assesses preverbal communications such as:

  • Babbling
  • Gesturing
  • Joint referencing
  • Turn taking
  • Vocabulary development such as naming objects, pictures, and actions
  • Morpho-syntactic development such as use of two-word utterances and use of plurals and verb tense

Receptive communication
Assesses preverbal behaviors and vocabulary development such as:

  • The ability to identify objects and pictures that are referenced
  • Vocabulary related to morphological development such as pronouns and prepositions
  • Understanding of morphological markers such as plurals and tense markings


Fine motor
Fine motor skills associated with:

  • Prehension
  • Perceptual-motor integration
  • Motor planning
  • Motor speed

Items measure age-appropriate skills including:

  • Visual tracking
  • Reaching
  • Object manipulation
  • Grasping
  • Children’s quality of movement
  • Functional hand skills
  • Responses to tactile information (sensory integration)

Gross motor
Items assess:

  • Static positioning (e.g. head control, sitting, standing)
  • Dynamic movement including locomotion (crawling, walking, running, jumping, walking up and down stairs)
  • Quality of movement (coordination when standing up, walking, kicking)
  • Balance
  • Motor planning
  • Perceptual-motor integration (e.g. imitating postures)

Developed by Stanley Greenspan, M.D., one of the world’s leading experts in child development.

  • Determines the mastery of early capacities of social-emotional growth
  • Monitors healthy social and emotional functioning
  • Monitors progress in early intervention programs
  • Detects deficits or problems with developmental social-emotional capacities
    • 0-3 months: Exhibits growing, self-regulation, and interest in the world
    • 4-5 months: Engages in relationships
    • 6-9 months: Uses emotions in an interactive, purposeful manner
    • 10-14 months: Uses a series of interactive, emotional signals or gestures to communicate
    • 15-18 months: Uses a series of interactive, emotional signals or gestures to solve problems
    • 19-30 months: Uses ideas to convey feelings, wishes, or intentions
    • 31-42 months: Creates logical bridges between emotions and ideas

Bayley–III™ Scoring Assistant® or Hand Scoring

You can hand-score the assessment or using the Scoring Assistant software for quick and accurate reporting.

Sample Reports

Bayley-III SA Parent Sample Report (PDF – 53kb)
Bayley-III SA Parent Sample Report Part 2 (PDF – 196kb)

Hardware Requirements

Windows XP, Vista or Windows 7

Bayley Scales of Infant and Toddler Development – Third Edition (Bayley-III)

Download PDF

Download PDF

Reference Materials

Tools & Utilities

Getting to Know Your Rolling Bag (PDF – 935 KB)

Bayley-III Observational Checklist (PDF – 149 KB)
Lists nearly 100 items that can be easily observed at any time during administration. Use the checklist to familiarize yourself with those items that can be observed outside the standard administration order, saving precious administration time. Make paper copies or use a grease pencil to note observed items, then later transfer to the master record form or input to the Scoring Assistant.

Bayley-III Brochure
Information on the newly revised Bayley Scales of Infant and Toddler Development — Third Edition (Bayley-III). Order hard copy using ISBN 999-8914-337

Technical Reports

Bayley-III Technical Report 1: Using the Bayley Scales of Infant and Toddler Development, Third Edition, to Assess Individuals with Severe Delays (PDF – 337 KB)

Bayley-III Technical Report 2: Factors Contributing to Differences Between Bayley–III and BSID–II Scores (PDF – 170 KB)


Visit our resource center to download the above information material.

Pearson Academy India, the training division of PCTA, conducts Bayley-III training workshops titled Bayley-III: Assessing Key Developmental Domains in Young Children.

Click here to learn more.

Complete Kit:

Includes: Administration Manual, Technical Manual, Cognitive, Language, and Motor Record Form, Pkg of 25, Stimulus Book, Picture Book, Manipulative Set, Social-emotional and Adaptive Behavior Questionnaire, Pkg of 25, Caregiver Report Form, Pkg of 25, and Rolling Case

ISBN: 9780158027241

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