This retrospective cohort study evaluated the incidence of preventable errors in a pediatric intensive care unit. Triggers were used to screen for possible errors (using a modification of a previously developed trigger tool), and trained physicians and nurses identified errors through chart review. Approximately one error occurred for every five patient-days, although more than three-quarters of these were minor errors that did not cause patient harm. The authors concluded that the trigger methodology was useful for identifying errors and systems issues contributing to errors in a pediatric population.