Most of the developmental instruments that measure cognitive development in children rely heavily on fine motor skills, especially for young children whose language skills are not yet well developed. This is problematic when evaluating the cognitive development of young children with motor impairment. The purpose of this study is to assess the need for a Low Motor adapation of a standardized instrument when testing children with motor impairment. To accomplish this, we have adapted the procedures, item instructions and play material of a widely used and standardized instrument, the Bayley Scales of Infant Development-Second Edition (BSID-II, Bayley 1993). The Original and the Low Motor versions were administered to 20 children experiencing typical development and 19 children with motor impairment within a period of two weeks. Results showed that children with motor impairments scored significantly higher on the Low Motor version of the Bayley Mental Scale than on the Original version: a difference of between 5 and 10 points when the score is expressed in terms of a developmental index score. Results from children with typical development support the assumption that item content and difficulty remain unchanged in the Low Motor version.