The objective of this overview is to summarize from systematic reviews the evidence on the effectiveness of using upper and lower limb casting or orthoses in children with cerebral palsy. We used computerized bibliographic databases to search for systematic reviews without any language restrictions. Identification, selection, quality assessment, and data extraction were performed independently by two investigators. Of the 40 identified reviews, 23 were selected for closer consideration, and five reviews met the inclusion criteria. The quality of existing systematic reviews and original studies included in our reviews varied widely. The following evidence was found: (1) casting of lower limbs has a short-term effect on passive range of movement; (2) orthoses that restrict ankle plantar flexion have a favorable effect on an equinus walk, but the long-term clinical significance is unclear; (3) evidence on managing upper limb problems with casting or splinting in children with cerebral palsy is inconclusive. Our conclusion is that there is a paucity of evidence from primary studies on the use of orthoses in children with cerebral palsy. More original, well-designed research is needed.