Context: Availability and usage of neuropsychological testing has increased in sports medicine. Understanding these commonly used measures is of great importance in order for the results to be interpreted properly. As neuropsychological tests become more available, their utilization will likely expand to include more young athletes, particularly those of high-school age. Objective: The purpose of this study was to determine the effects of age and practice on neuropsychological test performance. Design: Prospective repeated-measures design. Setting: Sports medicine research laboratory. Patients or Other Participants: Twenty college (20 ± 0.79 years) and 20 high school athletes (16.00 ± 0.86 years) with no known history of injury or disorder affecting neurocognition were included. Methods: Participants completed both ImPACT (Version 3) and a battery of traditional paper/pencil neuropsychological tests on three separate occasions approximately two days apart. Interventions: Subjects were divided into two groups based on age. High-school athletes were defined as 15-17 year-old athletes and college athletes were defined as athletes between the ages of 19 to 21. An equal number of males and females were in each group. Twoby-three mixed-model ANOVAs were used to analyze each outcome measure. Main Outcome Measures: Hopkins Verbal Learning Test–Revised (HVLT-R) immediate and delayed total recall, Brief Visuospatial Memory Test–Revised (BVMT-R) immediate and delayed total recall, Trail-Making Test Form B (TMT-B) total time, Symbol Digit Modalities Test (SDMT) total score, Stroop Test total score, and five ImPACT composite scores (verbal memory, visual memory, visual motor speed, reaction time, and impulse control). Results: We observed a significant effect of age for TMT-B total time (F1,38=6.16, P=0.018) with high-school athletes (49.66±14.50 sec) demonstrating a significantly greater overall time to completion compared to college athletes (41.46±13.71 sec). An effect of age was also observed for the ImPACT visual motor speed composite score (F1,38=5.029, P=0.031) with high-school athletes (42.01±7.34) demonstrating a significantly lower overall composite score compared to college athletes (46.44±6.48). A significant effect of test-time was observed for BVMT-R immediate (F2,76=3.19, P=0.046) and delayed (F2,64= 3.356, P=0.049), TMT-B (F2,66=73.432, P<0.001), Stroop Test (F2,76=96.851, P<0.001), and the ImPACT visual motor speed (F2,76=5.08, P=0.005). We observed no significant interactions for any measure. For all measures with a significant effect of time, scores significantly improved during the second session compared to the first indicating an overall practice effect. Conclusions: This study suggests that age affects two neuropsychological measures examined in this study. The clinician should be aware of this age difference when evaluating an athlete’s performance. Clinicians should also be mindful of improvement on many of the measures from the first session to the second in healthy individuals as no improvement in injured individuals may indicate a deficit. Our data also suggest baseline scores on these tests for younger athletes should be reassessed as they get older.