What is the impact of a hospital closure on patient health? The answer depends on whether the closing hospital is a low-mortality hospital or whether it is a high-mortality hospital, as well as the relative share of all hospital admissions that the closing hospital accounts for; closing small hospitals, however good, is unlikely to affect population health. Second, because high and low mortality hospitals are determined by calculating risk-adjusted mortality in claims data, it is also natural to ask whether risk-adjusted hospital performance measures good indicators of the causal impacts of hospitals on patient outcomes? While such measures are widely used for the purposes of quality improvement, public reporting and contracting, there is limited evidence on their causal validity. In this project, we use a quasi-experimental design to test whether these measures predict the impact of hospital closures on patient outcomes.