- OBJECTIVE: The objective of the study was to validate the parent-proxy reported Quality of Life in Childhood Epilepsy Questionnaire (QOLCE) in a sample of young adults with a history of childhood-onset epilepsy, allowing for the utilization of a consistent informant (the parent) across the youths' stages of development. The 55-item (QOLCE-55) and 16-item versions (QOLCE-16) were evaluated. METHODS: Data came from 134 young adults (aged 18.0 to 28.5 years) with childhood-onset epilepsy, recruited through community and tertiary care centers across Canada. Confirmatory factor analysis (CFA) was used to assess the higher-order factor structure of the QOLCE. Cronbach's alpha was used to evaluate internal consistency. Convergent validity was assessed by intraclass correlation coefficients (ICC) with the youth self-reported Quality of Life in Epilepsy Questionnaire (QOLIE-31-P). RESULTS: The higher-order factor structure of the QOLCE-55 and QOLCE-16 demonstrated adequate fit: QOLCE-55 comparative fit index (CFI) = 0.968, Tucker-Lewis index (TLI) = 0.966; and root mean square of approximation (RMSEA) = 0.061; QOLCE-16 CFI = 0.966, TFI = 0.959, RMSEA = 0.141. Higher-order factor loadings were strong, ranging from 0.71 to 0.90. Internal consistency was excellent for the total score (αQOLCE-55 = 0.97; αQOLCE-16 = 0.93) and good-excellent for each subscale (α > 78). Convergent validity was moderate to good for the total score (ICC > 0.72) and each subscale (ICC > 0.51). SIGNIFICANCE: These findings provide support for the use of the QOLCE-55 and QOLCE-16 among young adults with a history of childhood-onset epilepsy. Utilizing a consistent measure and informant across the stages of development is essential to reliably evaluate change over time.