The Agency for Healthcare Research and Quality's Patient Safety Indicators (PSIs) have been widely used to identify patient safety events in adult populations. Pediatric-specific PSIs have recently been developed as well. This study used PSI data from more than 400,000 pediatric hospital admissions to estimate the impact on costs and hospital length of stay associated with inpatient adverse events. These data provide the first estimate of the economic impact of preventable adverse events in children's hospitals. Based on similar research in adults, the Centers for Medicare and Medicaid Services recently decided to stop reimbursing hospitals for costs associated with certain adverse events.