Background: Three-dimensional echocardiography (3DE) evaluation of left ventricular (LV) volume and function in pediatrics compares favorably with cardiac magnetic resonance imaging. A multicenter trial with automated and semi-automated LV quantification allows for generation of normative data in large pediatric patients. The aims of this study were to evaluate the feasibility and reproducibility of measuring three-dimensional echocardiography (3DE) volumes and function in pediatric patients in a multicenter trial; to determine if automated software (without contouring edits) will improve the reproducibility in volume and function analysis; and thus establish normal z score values in this unique population. Methods: Six hundred and ninety-eight healthy children (ages 0 to 18 years) were recruited from 5 centers. Left ventricular (LV) 3DE was acquired from the 4-chamber view. A vendor independent software analyzed end-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV), and ejection fraction (EF) using automated and semi-automated quantification. Feasibility and reproducibility were assessed. Body surface area (BSA) based z-scores were generated. Results: Feasibility was 79% (523/658). Reproducibility was good between centers using the semi-automated quantification. Reproducibility was decreased using the automated quantification. Therefore, Z-scores were generated for ESV, EDV, and SV using the semi-automated method. Conclusions: 3DE can reliably evaluate LV volumes and EF in pediatric patients at different centers. We report pediatric Z-scores for normal LV volumes using the semi-automated method. Further optimization of technology will be necessary for reliable use of fully automated quantification by 3DE in children.