This study, conducted at the National Institutes of Health and the Children's National Medical Center, will evaluate how well different physicians agree in how they classify cerebral palsy subtypes based on patient examination. Cerebral palsy is divided into several subtypes, according to the primary underlying muscle abnormality and its distribution and severity. Classification of these subtypes is important for conducting rehabilitation research studies on patients with the same type of abnormality. However, doctors do not always classify cerebral palsy types in the same way. This study will examine methods for improving agreement among doctors in their classification of cerebral palsy subtypes.