Context: Neurocognitive test scores are often considered an important aspect of concussion management. To best use these data, clinicians must understand potential factors that may influence baseline performance on these tests. Objective: To determine preexisting factors that may influence performance on the Immediate Post-Concussion Assessment and Cognitive Test (ImPACT). Design: Cross-sectional study. Setting: Research laboratory. Patients or Other Participants: A total of 486 National Collegiate Athletic Association Division I collegiate student-athletes. Main Outcome Measure(s): To determine neurocognitive functioning and total symptom score at baseline, ImPACT was administered. Outcomes were verbal memory, visual memory, visual motor speed, reaction time, and total symptom score. A self-report demographic section at the beginning of ImPACT was used to gather information concerning previous treatment for headaches, migraines, and psychiatric conditions; diagnosis of attention-deficit/hyperactivity disorder; and exposure to previous strenuous exercise. We conducted multivariate analyses of variance to determine if the ImPACT composite and total symptom scores differed according to preexisting factors (P < .0083). Results: Sex showed an effect on verbal memory (P = .001), visual motor speed (P < .001), and reaction time (P = .006), with women performing better than men. A previous diagnosis of attention-deficit/hyperactivity disorder affected visual motor speed (P = .008). Previous treatment for headaches (P < .001), migraines (P = .001), a psychiatric condition (P < .001), or a diagnosis ofattention-deficit/hyperactivity disorder (P < .001) all showed effects on the total symptom score. Strenuous exercise did not affect neurocogntive performance or total symptom score. Conclusions: Based on our findings and the previous literature, we suggest that many preexisting factors influence baseline neurocognitive data. Baseline testing is an important aspect of concussion management. Sports medicine professionals should be cognizant of these factors when developing concussion-management protocols.