Objective: A commonly used sports-related concussion assessment program is the Immediate Post Concussion Assessment and Cognitive Testing battery (ImPACT). The reliability of ImPACT over time absent a concussive event is unclear; therefore, reliance on it as the primary clinical tool for managing sports-related concussion may be premature. This study examined test–retest indices of ImPACT pre- and post-season in non-concussed student athletes. Method: Participants were male and female high school (n = 49) and collegiate (n = 21) athletes tested twice using ImPACT, approximately 3–4 months between test sessions. Exclusion criteria included: (a) invalid baseline performance, (a) a concussive event within 24 months prior to testing, or (c) diagnosis of Attention-Deficit/Hyperactivity Disorder or learning disability. Results: Intraclass correlation coefficient values for visual processing speed (.72) and reaction time (.65) provided the highest reliability measures in this sample, whereas verbal memory (.42), visual memory (.49), cognitive efficiency index (.29), and concussion symptom scale (.47) scores indicated much lower reliability rates. Paired-samples t-test revealed significant change in visual processing speed performance and in total symptom scores (p < .01). After applying reliable change indices, 21% of the athletes showed reliable improvement in processing speed and 10% demonstrated reliable change in symptom scale scores. Conclusion: Due to the low-to-moderate reliability indices of ImPACT, findings of this study raise the importance of implementing other relevant computerized neurocognitive test batteries together with ImPACT not only for post-concussion but for pre-season evaluation of athletes. Further research is needed to establish psychometric properties of such assessment tools specific to concussion management.