Cerebral palsy (CP) is the most frequent motor disability in childhood, beginning early in development. The prevalence is declining and estimated to occur in about 1.6 per 1000 live births in high-income countries and higher in low- and middle-income countries. The motor impairment may be accompanied by disturbance of other functions, such as cognition, communication, sensation, perception, behaviour, and epilepsy. Multiple aetiologies result in brain injury that affects movement, posture, and balance. The evaluation of the child includes differentiating CP from progressive causes of neuromotor disability and spinal lesions; defining the musculoskeletal impairment and decide on ways of treatment; and identifying, evaluating, and addressing accompanying impairments. Assessment of muscle tone, strength, and selective motor control of specific muscle groups, contractures, posture, balance, and equilibrium responses, as well as severity of motor impairment. Classification according to predominant motor disorder into spastic, dyskinetic, or ataxic CP. Spastic CP is the most common type, classified as uni- or bilateral spastic CP. Dyskinetic CP is classified as choreoathetotic or dystonic CP. More than half of the patients also have additional clinical problems, affecting activity and participation. The present chapter has been in all fields revised.