Patient safety is a critical component of the U.S. healthcare system: thousands of people, including children, die or are injured yearly as a result of medical error. We designed and implemented a novel error-reporting tool for the pediatric intensive care unit. More errors were reported with the use of this paper-based tool than with the existing computerized error-reporting system. We also developed a scoring system to assess potential harm to the patient. The tool provided information about frequent and high-risk errors that guided successful improvements in patient care and safety and the achievement of measurable success.