This study investigated the psychometric properties of the Early Numeracy Screener. The Early Numeracy Screener is a teacher-administered, paper-and-pencil test measuring counting skills, numerical relational skills, and basic arithmetic skills. Three hundred and sixty-six first graders took the Early Numeracy Screener at the beginning of the school year. Confirmatory factor analysis was conducted in order to examine whether the screening tool was identified as a one-factor model or a three-factor model. The confirmatory factor analysis found evidence for the three-factor model, establishing construct validity. Evidence for criterion-related validity was found in crosstabulation and correlation with the national test measuring overall mathematics performance taken towards the end of the school year. The Early Numeracy Screener may serve as an indicator of young children's performance in early numeracy. The brevity and ease of use of the Early Numeracy Screener make it suitable for classroom instructional settings.