To discover factors that may contribute to a child’s risk for error during hospitalization, this study identified categories of child-specific factors and tested them using selected cases. The factors included both physical and developmental characteristics of a child as well as a child's minor legal status. These factors contributed to nearly half of the identified patient safety problems. While developmental attributes represented the most common factor associated with harm, the overall level of harm was higher when given any child-specific factor. The authors emphasize that important patient-specific factors, whether in the elderly or in children, present an opportunity to design tailored interventions to reduce patient safety problems.