Objective: To systematically evaluate the level of evidence of the clinimetric properties of measures of aerobic and anaerobic capacity used for children with cerebral palsy (CP). Data Sources: A systematic search of databases PubMed, Embase, SPORTDiscus, and PsycINFO through April 2011 was performed. Study Selection: Two independent raters identified and examined studies that reported laboratory- or field-based measures of maximal aerobic or anaerobic capacity in children with CP aged 5 to 14 years. Data Extraction: The COnsensus-based Standards for the selection of health status Measurement INstruments (COSMIN) checklist was used by 2 independent raters to evaluate the methodologic quality of the included clinimetric studies and to identify measures used in these studies. Data Synthesis: Twenty-four studies that used a maximal aerobic or anaerobic capacity measure were identified. Five studies reported clinimetric properties for 5 measures (2 aerobic and 3 anaerobic measures). Methodologic quality was excellent in 3 studies, showing good validity and reliability of field-based aerobic (Shuttle Run Test) and anaerobic (Muscle Power Sprint Test) measures. The studies on laboratory-based measures were rated fair, mainly because of inadequate statistics. The level of evidence was strong for good validity and reliability of the field-based tests. The level of evidence was unknown for validity and low to moderate for good reliability of laboratory-based tests. Conclusions: There is a paucity of research on the clinimetric properties of measurement instruments to assess aerobic and anaerobic capacity for children with CP. Further clinimetric studies of laboratory-based measures in children with CP at all Gross Motor Function Classification System (GMFCS) levels, and clinimetric studies of field-based measures in children who are classified as GMFCS levels III to V are required. © 2013 American Congress of Rehabilitation Medicine.