This study’s objectives were to assess the test-retest reliability and concurrent validity of the King-Devick Test (KDT) during concussion screening and to analyze potential sport-specific differences in test performance across two sports. Two hundred and sixty-six high school male American football and soccer players recruited from four area high schools participated prior to the fall sports season. Main outcome measures included the KDT and Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT). KDT performance demonstrated significant correlations with the ImPACT visual motor speed composite scores, reaction time, Cognitive Efficiency Index and age. Significant baseline differences were noted on the KDT between football and soccer players. The KDT demonstrates concurrent validity with three neurocognitive domains on the ImPACT. Significant differences in baseline King-Devick Test scores were found between football and soccer players and may be related to the neurocognitive demands of the sport.