Aim: The aim of this study was to provide reference values of anaerobic performance and agility in a group of children and adolescents with spastic cerebral palsy (CP). Method: A total of 300 children (184 males, 116 females) with spastic CP were recruited from 26 rehabilitation centres in six different countries. Of these, 215 were classified at GMFCS level I (mean age 11y 2mo, SD 3y, range 6-18y) and 85 were classified at GMFCS level II (mean age 11y; SD 3y 1mo, range 6-18y). The children performed the Muscle Power Sprint Test (MPST) and the 10x5m sprint test in a standardized manner. To establish reference values, reference curves were created using generalized additive models for location, scale, and shape. Results: Height-related reference curves were created based on performance on the two tests. Interpretation: This study provides height-related reference values for anaerobic performance and agility for children and adolescents with CP classified at GMFCS levels I and II. These curves are clinically relevant and provide a user-friendly method in the interpretation of anaerobic performance and agility for children with spastic CP.