OBJECTIVES: The purpose of this study was to examine the one-year test-retest reliability of Child Sport Concussion Assessment Tool 5th Edition component scores and provide recommendations for interpreting change on its component tests. DESIGN: A prospective cohort study was conducted across two years via the Advancing Healthcare Initiatives for Underserved Students (ACHIEVES) Project. METHODS: Participants were 219 children (ages 11 to 12, M = 11.7, SD = 0.5; 52.1% girls, 47.9% boys) playing competitive school-sponsored sports in nine middle schools across a large public-school division in Virginia, USA during the 2017-2018 and 2018-2019 academic years. Athletic Trainers administered the baseline Child Sport Concussion Assessment Tool 5th Edition each year. RESULTS: Test-retest reliability estimates for each Child Sport Concussion Assessment Tool 5th Edition component were low to moderate (ICCs=0.40-0.55). A minority of middle school athletes (15-31%) scored within a different normative classification range upon re-assessment. The following test-retest difference scores occurred in 20% or fewer of the sample: +5 total symptoms, +7 symptom severity, -2 in the Standardized Assessment of Concussion - Child Version total score, and +4 total Modified Balance Error Scoring System balance errors. CONCLUSIONS: Child Sport Concussion Assessment Tool 5th Edition component scores had poor to moderate test-retest reliability coefficients over a one-year period, though most children were classified as falling within the same interpretive category upon re-testing based on local norms. We report the raw score changes that were uncommon in our sample of uninjured children to help clinicians identify changes that might be clinically meaningful.