We examined the validity of ImPACT, a computerized test battery, for measuring the effects of sportsrelated concussion. The 120 high school and college athletes completed preseason testing and were evaluated within 3 days of sustaining a concussion. Concurrent criterion validity was examined by determining whether the composite scores were sensitive to the acute effects of concussion. After their concussions, athletes reported significantly more symptoms (P <.00001, d=.066), reaction time (P<.014, d=.27) , and processing speed. (P<.011, d=.28). Divergent validity was examined through an intercorrelation matrix of the composite scores at preseason and at postinjury. The resulting small correlations indicate that the composite scores do not have much shared variance, and thus appear to be measuring different things. Convergent validity was examined by correlating the composite scores with specific items from the postconcussion scale, for the postinjury assessment. There were medium to high correlations (r’s from .53 to .83) between total symptoms and selected individual items (i.e., vomiting, balance problems, poor concentration, poor memory, light sensitivity, noise sensitivity, and feeling more emotional). The memory composite score was significantly correlated with the poor memory (r = −.40) and poor concentration (r = −.40) items, less correlated with the balance problems (r = −.27) and light sensitivity (r = −.32) items, and uncorrelated with the remaining physical and emotional items.