This article reviews the historical background, classification, and etiology of cerebral palsy (CP), the most common motor disability of childhood. The various methods employed to measure the prevalence of CP in the population are examined. Causes of CP are numerous, and the etiology multi-factorial. Risk factors are categorized by the timing of their proposed occurrence: prenatal, perinatal, and postnatal. The leading prenatal and perinatal risk factors for CP are birth weight and gestational age. Other risk factors include neonatal encephalopathy, multiple pregnancy, infection and inflammation, and a variety of genetic factors.