BACKGROUND: Because young children cannot self-report symptoms, there is a need for parent surrogate reports. Although early work suggested parent-child alignment for eosinophil esophagitis (EoE) patient-reported outcomes (PROs), the longitudinal alignment is unclear. OBJECTIVE: We sought to assess the agreement and longitudinal stability of PROs between children with EoE and their parents. METHODS: A total of 292 parent-child respondents completed 723 questionnaires over 5 years in an observational trial in the Consortium of Eosinophilic Gastrointestinal Disease Researchers. The change in and agreement between parent and child Pediatric Eosinophilic Esophagitis Symptom Score version 2 (PEESSv2.0) and Pediatric Quality of Life Eosinophilic Esophagitis Module (PedsQL-EoE) PROs over time were assessed using Pearson correlation and Bland-Altman analyses. Clinical factors influencing PROs and their agreement were evaluated using linear mixed models. RESULTS: The cohort had a median disease duration equaling 3.7 years and was predominantly male (73.6%) and White (85.3%). Child and parent PEESSv2.0 response groups were identified and were stable over time. There was strong correlation between child and parent reports (PEESSv2.0, 0.83;PedsQL-EoE, 0.74), with minimal pairwise differences for symptoms. Longitudinally, parent-reported PedsQL-EoE scores were stable (P ≥ .32), whereas child-reported PedsQL-EoE scores improved (P = .026). A larger difference in parent and child PedsQL-EoE reports was associated with younger age (P < .001), and differences were driven by psychosocial PRO domains. CONCLUSIONS: There is strong longitudinal alignment between child and parent reports using EoE PROs. These data provide evidence that parent report is a stable proxy for objective EoE symptoms in their children.