ObjectivesDevelop a score summarising how successfully a child with any surgical condition has been treated, and test the clinical validity of the score.DesignDiscrete choice experiment (DCE), and secondary analysis of data from six UK-wide prospective cohort studies.Participants253 people with lived experience of childhood surgical conditions, 114 health professionals caring for children with surgical conditions and 753 members of the general population completed the DCE. Data from 1383 children with surgical conditions were used in the secondary analysis.Main outcome measuresNormalised importance value of attribute (NIVA) for number/type of operations, hospital-treated infections, quality of life and duration of survival (reference attribute).ResultsQuality of life and duration of survival were the most important attributes in deciding whether a child had been successfully treated. Parents, carers and previously treated adults placed equal weight on both attributes (NIVA=0.996; 0.798 to 1.194). Healthcare professionals placed more weight on quality of life (NIVA=1.469; 0.950 to 1.987). The general population placed more weight on survival (NIVA=0.823; 95% CI 0.708 to 0.938). The resulting score (the Children’s Surgery Outcome Reporting (CSOR) Treatment Success Score (TSS)) has the best possible value of 1, a value of 0 describes palliation and values less than 0 describe outcomes worse than palliation. CSOR TSSs varied clinically appropriately for infants whose data were included in the UK-wide cohort studies.ConclusionsThe CSOR TSS summarises how successfully children with surgical conditions have been treated, and can therefore be used to compare hospitals’ observed and expected outcomes.