Physical therapy is considered to be an important part of the management of cerebral palsy (CP); but what type of therapy, at what intensity, and for how long? These are questions which are not easily answered. Much valid criticism is directed towards the so-called ‘named’ therapy approaches because of the lack of a sound scientific basis and proof of efficacy. There is certainly little or no evidence to support the effectiveness of any particular approach, nor is there evidence to demonstrate superiority of one approach over another. Increasingly, therapists are being urged to adopt evidence-based intervention, but is there adequate, robust evidence available to enable them to do this? And how can available evidence be translated into effective practice? Certainly there are pockets of evidence to support the use of various forgotten and emerging modalities, such as muscle strengthening, constraint-induced movement therapy, and task-specific learning. This is encouraging; but such evidence cannot be generalized to all children with CP, particularly those who are classified as level IV and V on the Gross Motor Function Classification System, or to those who reside in disadvantaged environments. How can therapy for children with a multifaceted and complex disorder such as CP reach the stage where it is based on sound evidence?