Background and Purpose— Rapid recognition of those at high risk for malignant edema after stroke would facilitate triage for monitoring and potential surgery. Admission data may be insufficient for accurate triage decisions. We developed a risk prediction score using clinical and radiographic variables within 24 hours of ictus to better predict potentially lethal malignant edema. Methods— Patients admitted with diagnosis codes of cerebral edema and ischemic stroke, NIHSS score (National Institute of Health Stroke Score) of ≥8 and head computed tomographies within 24 hours of stroke onset were included. Primary outcome of potentially lethal malignant edema was defined as death with midline shift ≥5 mm or decompressive hemicraniectomy. We performed multivariate analyses on data available within 24 hours of ictus. Bootstrapping was used to internally validate the model, and a risk score was constructed from the results. Results— Thirty-three percent of 222 patients developed potentially lethal malignant edema. The final model C statistic was 0.76 (confidence interval, 0.68–0.82) in the derivation cohort and 0.75 (confidence interval, 0.72–0.77) in the bootstrapping validation sample. The EDEMA score (Enhanced Detection of Edema in Malignant Anterior Circulation Stroke) was developed using the following independent predictors: basal cistern effacement (=3); glucose ≥150 (=2); no tPA (tissue-type plasminogen activator) or thrombectomy (=1), midline shift >0 to 3 (=1), 3 to 6 (=2), and 6 to 9 (=4); >9 (=7); and no previous stroke (=1). A score over 7 was associated with 93% positive predictive value. Conclusions— The EDEMA score identifies patients at high risk for potentially lethal malignant edema. Although it requires external validation, this scale could help expedite triage decisions in this patient population.