Over the last 25 years the definition and classification of cerebral palsy (CP) have evolved, as well as the approach to rehabilitation. CP is a disorder of the development of movement and posture, causing activity limitations attributed to nonprogressive disturbances of the fetal or infant brain that may also affect sensation, perception, cognition, communication, and behavior. Motor control during reaching, grasping, and walking are disturbed by spasticity, dyskinesia, hyperreflexia, excessive coactivation of antagonist muscles, retained developmental reactions, and secondary musculoskeletal malformations, together with paresis and defective programing. Weakness and hypoextensibility of the muscles are due not only to inadequate recruitment of motor units, but also to changes in mechanical stresses and hormonal factors. Two methods, the General Movements Assessment and the Test of Infant Motor Performance, now permit the early detection of CP, while the development of valid and reliable outcome measures, particularly the Gross Motor Function Measure (GMFM), have made it possible to evaluate change over time and the effects of clinical interventions. The GMFM has further led to the development of predictive curves of motor function while the Gross Motor Classification System and the Manual Ability Classification System provide standardized means to classify the severity of the movement disability. With the emergence of the task-oriented approach, the focus of therapy in rehabilitation has shifted from eliminating deficits to enhancing function across all performance domains by emphasizing fitness, function, participation, and quality of life. There is growing evidence supporting selected interventions and interest for the therapy and social integration of adults with CP.