Bayley Scales of Infant and Toddler Development | Fourth Edition (Bayley™-4)

The Bayley Scales of Infant and Toddler Development, Fourth Edition (Bayley-4) is the standard developmental evaluation for babies and toddlers, covering roughly 16 days through 42 months. It is used to find out whether a child is developing as expected and, if not, in which areas.

Five domains are assessed. Cognitive, Language, and Motor are administered directly by the examiner through play-based tasks with a standardized set of toys and materials. Social-Emotional and Adaptive Behavior are caregiver questionnaires, drawing on what a parent sees at home rather than in a clinic room. Items are scored as mastered, emerging, or absent, and results convert to scaled and composite scores. Adjusting for prematurity is recommended and the manual specifies for how long by domain.

Licensing Notes: Purchase is qualification-restricted, and score reports carry an explicit reproduction restriction.

Learn More: Only the two caregiver questionnaires — Social-Emotional and Adaptive Behavior — can be completed remotely, via Q-global. The Cognitive, Language, and Motor scales require in-person standardized administration. That makes a hybrid workflow practical: the caregiver completes their portion before or after an in-person session.