Using data from the Colorado and Utah Medical Practice Study, this study suggests particularly high rates of adverse events in adolescent populations compared with other age groups of children. Investigators also used critical incident analysis to demonstrate that adolescent-specific factors accounted for more than half of the patient safety problems identified. The authors discuss recommendations for interventions to reduce such safety problems using their combination of quantitative and qualitative data. While results were generated from retrospective chart reviews, this study represents the first population-based estimate of adverse events in this particular patient population.