Objective: The purpose of this study was to evaluate the interplay between speed and accuracy (cognitive efficiency) on the Symbol Match subtest of the ImPACT test battery. The Symbol Match subtest is similar in structure to the Symbol Digit Modalities Test, but measures average time to respond in milliseconds. This task also includes a memory component (items accurately recalled). Within this context, cognitive efficiency incorporates both the accuracy of how a task was performed and the speed at which it was performed. This is important because concussed athletes have been observed to sacrifice either speed or accuracy when faced with a difficult task. Method: A Cognitive Efficiency Index (CEI) score was calculated using measures of speed and accuracy on ImPACT for a sample of 252 concussed athletes (100 males and 152 females). The average age of the concussed sample was 17.45 (2.54) years. The average number of reported prior concussions was .94 (range ¼ 0–15), and the average time between injury and post-injury 2009 Annual Meeting Abstracts / Archives of Clinical Neuropsychology 24 (2009): 431–540 509 evaluation was 39.2 days (range ¼ 1–1,060 days). The concussed group was compared with an age-matched non-injured control group (N ¼ 84). Results: Concussed athletes performed significantly more poorly than did non-injured athletes on the CEI (F ¼ 5.33, p , .02). There was no significant difference between male and female athletes on the CEI (F ¼ .25 p , .64). Conclusions: The CEI appears to provide useful information in the evaluation of the interplay of speed and accuracy following concussion. Thus, this measure may provide a useful metric of the evaluation of recovery post-injury.