Trauma triage scores, severity of illness measures, and mortality prediction models quantitate severity of injury and stratify patients according to a specified outcome. Triage scoring systems are typically used to assist prehospital personnel determine which patients require trauma center care, but they are not recommended as the sole determinant of triage. Severity of illness measures and mortality prediction models are used in clinical and health services research for risk-adjusted outcomes analyses and institutional benchmarking. As clinicians and researchers, it is imperative that we be knowledgeable of the methodologies and applications of these scoring and risk prediction systems to ensure their quality and appropriate utilization.