OBJECTIVE: When test results are interpreted based on the norms of the U.S. population, misdiagnoses of neurocognitive impairment could occur with subgroups of individuals whose demographic characteristics differ from the overall population. The present study compared locally-based normative test data of the Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) of high school athletes in Hawaii, where diverse ethnicity and bilingualism are prominent, versus published test norms. METHOD: 8637 high school athletes in Hawaii underwent ImPACT baseline testing. Non-parametric group comparisons of age, sex, and language groups were performed. Classification ranges for the ImPACT Composite scores and Total Symptom of the Hawaii sample were presented in percentile ranks that corresponded to the published ImPACT normative tables. RESULTS: Mann-Whitney U Test indicated significant differences in ImPACT Verbal Memory, Visual Memory, Visual Motor Speed, and Reaction Time Composite scores between age groups and sexes, although the effect sizes were small. Kruskal-Wallis H Test indicated no differences among the language groups. Percentile ranks of the Hawaii scores were predominantly similar to the ImPACT norms, except for Visual Motor Speed in the Impaired and Borderline ranges. CONCLUSION: The findings suggest that locally based normative data should be considered for sub-populations that may differ from the general population. Language factors, such as bilingualism, did not have significant effect on the ImPACT scores.