The Chinese version of the GMFCS-ER is a valid measure of functional ability in school children with CP and reliable enough for use by Chinese healthcare providers and parents. Effects of environmental and personal factors should be considered when practicing GMFCS-ER assessment. Implications for Rehabilitation Cerebral palsy. Research about GMFCS-ER is needed to promote a more extensive use of GMFCS-ER in China for school children with CP. The Chinese version of the GMFCS-ER is a valid measure of functional ability in school children with CP and reliable enough for use by Chinese healthcare providers. Effects of environmental and personal factors should be considered when performing the GMFCS-ER assessment.