Differences in performance on the Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) have been reported between Spanish and English-speaking individuals. The current study addressed whether these differences could be accounted for by primary language preference, language of ImPACT administration, or a combination of the two. Differences in cognitive and symptom domain scores from ImPACT baseline testing were compared for 264 high school athletes. These high school athletes were either monolingual English speakers who were tested in English (EE; n = 88), bilingual Spanish/English speakers who were tested in English (SE; n = 88), or monolingual and bilingual Spanish speakers who were tested in Spanish (SS; n = 88). These participants were selected from a larger sample and individually matched on variables that could contribute to differences in baseline ImPACT performance. Results indicated the EE group performed better on the Visual Motor Speed and Reaction Time cognitive composites than the SE and SS groups. The SS and SE groups also reported significantly more affective symptoms than the EE group, although group differences in the PCSS total score and other domain scores were not significant. These results provide confirmation of differences between language groups’ cognitive and symptom reporting on ImPACT, and further suggest that these differences are not primarily accounted for by confounding factors, language of test administration, or primary language preference. Additional research is needed to determine whether these ImPACT cognitive and symptom differences result from test bias, linguistic influences, cultural considerations, or a combination of these and other factors.