The purpose of the study was to determine whether particular aspects of movement control influenced the performance of 2-year-old children on a standard developmental test, and thus influenced assessments of intellectual progress based on that test. Six cerebral-palsied (CP) children were compared with six children not suffering motor system dyscontrol (NCP) on a brick tower-building task. Results showed that the most competent CP child achieved the same level as the least competent NCP child. Two distinct sub-groups were found within the CP group--one which achieved acceptable age-related performance with slightly lower levels of control than the NCP group and another which showed very low levels of control especially in digital manipulation of the test objects. (Author/JDD)