This article investigates the validity of the Minor Injury Severity Scale (MISS) as a behavioral, objective measure of injury-induced tissue damage. The MISS is a scale that allows a coder to quantify the physical signs of an injury (e.g., bleeding, swelling) for 22 different kinds of minor injury. Inter-coder reliability of the MISS, as well as experts' and novices' ratings of ease of use, accuracy, and applicability were examined. Severity rankings made by school nurses with extensive experience assessing and treating injuries served as the criterion. Nurses' severity rankings on an open-ended Visual Analogue Scale (VAS) and the MISS were compared with the VAS and MISS rankings of laypersons having no previous medical training. These data suggest that the MISS has adequate construct validity and is more reliable than the VAS for layperson use. In addition, the majority of coders found the MISS to be easier to use, to be more accurate, and to have more practical applicability than the VAS, irrespective of medical expertise. Limitations of this study and future potential applications of the MISS are also discussed.