Pediatric medication errors remain an important focus of safety initiatives. This systematic review examined the extent of preventable patient harm from medication errors for pediatric inpatients. The 22 included studies reported incidence rates ranging from 0 to 74 preventable adverse drug events per 1000 inpatient days. Across all studies, most errors were minor and did not result in patient harm. Use of health information technology was associated with less harm. Emphasizing the challenges of detecting and reporting errors, a related editorial calls for standardizing descriptions of preventable adverse events and harm in pediatrics. A WebM&M commentary addressed the high potential for weight-based medication errors in pediatrics and provided recommendations to help mitigate this risk.