To develop and validate a new measurement tool designed to assess self-reported distress responses after traumatic physical injury.A mixed-methods study design was used. Development of the Injury Distress Index (IDI) included input from patients and experts and a comprehensive literature review. The IDI and validity measures were administered by a trained research assistant at bedside within 1 week of admission. The internal structure (exploratory factor analyses [EFAs]), reliability (internal consistency), and associations with other variables (construct and criterion validity) were examined.Hand, multiple trauma, and burn services at a large southeastern level-1 trauma center.Multicultural cohort of 169 traumatically injured adults (31% hand, 21% burn, 48% multiple trauma).Not applicable.IDI, Trauma Symptom Checklist-40, Short-Form McGill Pain Questionnaire, Perceived Stress Scale-10, Life Orientation Test-Revised, General Perceived Self-Efficacy Scale, Drug Abuse Screening Test-10, Brief Michigan Alcoholism Screening Test, Abbreviated Injury Scale, hospital length of stay (LOS), postdischarge emergency department visits, and days readmitted to hospital postdischarge.An item pool was developed from patient, expert, and literature review data. EFAs extracted 3 separate factors for posttraumatic stress (avoidance and numbing, re-experience, and hyperarousal: coefficient range, .31-.98), which is consistent with conceptual and diagnostic criteria. EFAs also produced single factors of depression (coefficient range, .44-.72), anxiety (coefficient range, .50-.75), and pain (coefficient range, .57-.79). Most IDI scales (except anxiety) could be differentiated between different levels of injury severity. IDI scales and subscales correlated highly and in a convergent pattern with validity measures of posttraumatic stress (r range, .18-.50), depression (r range, .24-.52), anxiety (r range, .30-.57), and pain (r range, .10-.42), as well as theoretically related variables, such as general distress (r range, .32-.56), self-efficacy (r range, -.15 to -.39), and optimism (r range, -.21 to -.45). IDI scales correlated in a discriminant pattern with measures of drug and alcohol abuse (r range, .02-.07; r range, .09-.21, respectfully). Concurrent and predictive validity evidence was also supported with small associations with injury severity (r range, .16-.30), hospital LOS (r range, .05-.21), number of emergency department visits postdischarge (r range, -.05 to .27), and number of days readmitted to the hospital postdischarge (r range, .05-.21). Cronbach alpha coefficients were within the acceptable range (alpha range, .75-.92).A new tool to examine injury-related distress after traumatic physical injury has been developed. Results suggest that IDI scores showed acceptable reliability and validity coefficients with this multicultural sample. Additional validation studies are recommended with larger sample sizes using similar populations to confirm these findings.