The recently proposed definition and classification of cerebral palsy (CP) is still up for debate – see the correspondence in this issue – and additional comments via the Castang website are warmly invited before the final version is completed next month (www.castangfoundation.net/workshops_washington_public.asp). The Castang Foundation funds ‘research into the causes of CP and other neurodevelopmental disorders leading to their prevention’. Rightly, the document does not specify the ‘non-progressive disturbances’ to which CP is attributed, with the exception of cerebral dysplasia. It is unclear why this should be picked out since in developed countries white matter disorders and perinatal vascular events currently appear more common. Data from other parts of the world are less available, but emphasize the continuing importance of post-neonatal causes. As the relative importance of different disturbances changes with medical knowledge, geography, and over time, a non-specific definition is understandable.