Bayley Scales of Infant Development

The Bayley Scales of Infant Development (BSID-III is the current version) is a standard series of measurements originally developed by psychologist Nancy Bayley used primarily to assess the motor (fine and gross), language (receptive and expressive), and cognitive development of infants and toddlers, ages 0-3. This measure consists of a series of developmental play tasks and takes between 45 - 60 minutes to administer. Raw scores of successfully completed items are converted to scale scores and to composite scores. These scores are used to determine the child's performance compared with norms taken from typically developing children of their age (in months). The assessment is often used in conjunction with the Social-Emotional Adaptive Behavior Questionnaire. Completed by the parent or caregiver, this questionnaire establishes the range of adaptive behaviors that the child can currently achieve and enables comparison with age norms.