ABSTRACT: Purpose:The purpose of this study was to characterize the differences in myopic progression in children by race/ethnicity and age. Methods:Patients enrolled in Kaiser Permanente Southern California between 2011 and 2016 and between the ages of 4 and 11 years old with a documented refraction between -6 and -1 diopters (Ds) were included in this retrospective cohort study. Patients with a history of amblyopia, strabismus, retinopathy of prematurity, or prior ocular surgery were excluded from analyses. Patients' race/ethnicity and language information were used to create the following groups for analysis: white, Black, Hispanic, South Asian, East/Southeast Asian, Other Asian, and other/unknown. A growth curve analysis using linear mixed-effects modeling was used to trace longitudinal progression of spherical equivalents over time, modeled by race/ethnicity. Analyses adjusted for potential confounders, including body mass index (BMI), screen time, and physical activity. Results:There were 11,595 patients who met the inclusion criteria. Patients were 53% girls, 55% Latino, 15% white, 9% black, 9% East/Southeast Asian, and 2% South Asian. Mean age (standard deviation [SD]) at the time of initial refraction was 8.9 years (1.6 years). Patients had an average (SD) of 3.4 (1.5) refractions, including the baseline measurement, during the study period. A three-way interaction model that assessed the effects of age at baseline, time since baseline, and race/ethnicity found that children of East/Southeast Asian descent showed significantly faster myopia progression across time (P < 0.001). East/Southeast Asian patients who presented with myopia between 6 to < 8 years progressed similarly to white patients in the same age group and significantly faster compared with white patients in other age groups. Conclusions:Myopia progression differed significantly between East/Southeast Asian and white patients depending on the patients' age.