CONTEXT: Student-athletes are commonly administered the Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) battery at preseason baseline and postconcussion. The ImPACT is available in many languages, but few researchers have examined differences in cognitive performances and symptom ratings based on the language of administration. OBJECTIVE: To examine differences in ImPACT neurocognitive composites and symptom reporting at preseason baseline testing between student-athletes who completed ImPACT in Spanish versus English. DESIGN: Cross-sectional study. SETTING: Preseason baseline testing for a high school concussion-management program in Maine. PATIENTS OR OTHER PARTICIPANTS: Adolescent student-athletes who completed testing in Spanish (n = 169) and English (n = 169) were matched on age, gender, and health and academic history. Language groups were compared on each outcome for the full sample and for gender-stratified subsamples. MAIN OUTCOME MEASURE(S): Neurocognitive composite scores and individual and total symptom severity ratings from the ImPACT battery. RESULTS: Athletes tested in Spanish displayed lower levels of neurocognitive performance on 2 of 5 composite scores (visual motor speed: P < .001, d = 0.51; reaction time: P = .004, d = 0.33) and reported greater symptom severity (P < .001, r = 0.21). When the analyses were stratified by gender, similar visual motor speed differences were observed between language groups among boys (P = .001, d = 0.49) and girls (P = .001, d = 0.49), whereas reaction time showed a larger group difference for boys (P = .012, d = 0.42) than for girls (P = .128, d = 0.21). Language-group differences in symptom reporting were similar for boys (P = .003, r = 0.22) and girls (P = .008, r = 0.21), with more frequent endorsement of physical and affective symptoms by athletes tested in Spanish. CONCLUSIONS: Language-group differences in total symptom severity were small (r = 0.21) and in neurocognitive performances were small to medium (d = 0.05-0.51). Versus previous authors who compared athletes tested in Spanish and English with ImPACT, we observed smaller effects, which may be attributable to close matching on variables related to neurocognitive performances and symptom reporting.