Nearly 2 decades into the patient safety movement, measurement of safety events remains a challenge. In particular, methods to measure safety that are patient-centered and can be compared across organizations are not standardized. This study proposes adverse event–free admissions as a potential measure of safety, defining the term as any hospitalization in which the patient does not experience a preventable adverse event. In analyzing nearly 24 million Medicare admissions, investigators found that only 64% were adverse event-free. When evaluating admissions for colorectal surgical procedures, the authors were able to identify a subset of hospitals with markedly higher rates of adverse events using this metric, implying that the measure may be suitable for interhospital comparisons. The recent National Patient Safety Foundation report, Free From Harm, identified safety measurement as a high priority for the field, and this study is a promising step forward. A previous PSNet perspective discussed challenges associated with safety measurement.