OBJECTIVES: A dearth of standardized assessment tools exists to properly assess and triage mild traumatic brain injury (mTBI) in primary care and acute care settings. This article presents evidence of appropriate psychometric properties for the Acute Concussion Evaluation (ACE), a new structured clinical interview. PARTICIPANTS: Parent informants of 354 patients, aged 3 to 18 years, with suspected mTBI completed the ACE via telephone interview. MEASURE: Acute Concussion Evaluation. RESULTS: Evidence is presented for appropriate item-scale membership, internal consistency reliability as well as content, predictive, convergent/divergent, and construct validity of the ACE symptom checklist. CONCLUSIONS: Overall, the ACE symptom checklist exhibits reasonably strong psychometric properties as an initial assessment tool for mTBI. [ABSTRACT FROM AUTHOR]