Executive function (EF) has a critical role in school success, both academic and social-emotional. Nevertheless, there is a lack of evidence on developmentally sensitive measures of EF for young children and on the feasibility of assessing EF for early childhood screening. This study assessed the screening potential of EF tasks, including the National Institutes of Health (NIH) Toolbox measures of EF, Flanker and Dimensional Change Card Sort (DCCS) with developmental extensions (Dext versions). EF measures were added to routine screening of children 3-6 years old in a large urban school district, providing promising data on the validity of the EF measures and their added value beyond traditional screening measures utilized by this district. EF uniquely predicted growth in learning across the kindergarten year. Results also provided evidence that Dext versions of the NIH Toolbox EF measures effectively lower the floor of the Flanker and DCCS tasks, which is essential for their utility in early childhood screening. Findings indicate that EF measures capture a wide range of variability, can be administered during routine screening, show construct validity, and provide unique predictive value for school outcomes. (author abstract)