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

The Bayley Scales of Infant and Toddler Development – Third Edition (Bayley-III; Bayley, 2005) may be used to identify developmental delays, chart a child’s progress, and teach parents about the child’s development.


The test is designed to be used with children ages 1 to 42 months. It consists of five scales: Cognitive, Language (Receptive and Expressive), Motor (Fine and Gross), Social-Emotional, and Adaptive Behavior (Conceptual, Social, and Practical). It also includes a test observations measure to aid in intervention planning. This addition includes growth scores, index scores (standard scores), subtest scaled scores, and percentiles. The Adaptive Behavior scale of the Bayley-III was adapted from the Parent/Primary Caregiver form of the Adaptive Behavior Assessment System – Second Edition (ABAS-II; Harrison & Oakland, 2003).


Author (yr) Age Range (yrs) Method of Administration/Format Approx. Time to Administer Subscales
Bayley Scales of Infant and Toddler Development – Third Edition (Bayley-III) Birth – 3 yrs., 6 Mos.

Individually administered by clinician in play-based format for Cognitive, Language, and Motor (Fine/Gross) Scales; caregiver questionnaire for Social-Emotional and Adaptive

Functioning (Conceptual, Social, and Practical).

Yields scaled scores, composite scores, and percentile ranks, growth and developmental age scores for Cognitive, Language and Motor.
50 min. for 1– 12 mos.; 90 min. for 13–42 mos.

Cognitive; Language

(Receptive, Expressive, Total); Motor (Fine-Motor, Gross-Motor, Total); Adaptive Behavior (Communication,

Community Use, Functional Pre-Academics, Home

Living, Health and Safety, Leisure, Self-Care, Self-Direction, Social, Motor, Total)

Availability: The Psychologic Corporation (Harcourt Assessment/Pearson)

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