A parentally administered cognitive development assessment for children from 10 to 24 months.

The Cognitive Development Questionnaire (CDQ) allows accurate assessment of cognitive development of children from 10 to 24 months by parents and caregivers in the home. It takes between 1 and 2h to complete over about a week. Three phases of work are described, in which the instrument is progressively refined to improve its validity and reliability. This resulting version of the CDQ shows excellent correlation with age, and with the Mental Scale of the Bayley Scales of Infant Development (Bayley, 1993). The CDQ thus offers researchers and clinicians a useful alternative to professionally administered cognitive assessment in infancy.