Background-The goal of this study was to create a comprehensive, integer-weighted predictive scale of adverse events after carotid endarterectomy (CEA), which may augment risk stratification and patient counseling. Methods and Results-The targeted carotid files from the prospective NSQIP (National Surgical Quality Improvement Program) registry (2011-2013) comprised the derivation population. Multivariable logistic regression evaluated predictors of a 30-day adverse event (stroke, myocardial infarction, or death), the effect estimates of which were used to build a weighted predictive scale that was validated using the 2014 to 2015 NSQIP registry release. A total of 10 766 and 8002 patients were included in the derivation and the validation populations, in whom 4.0% and 3.7% developed an adverse event, respectively. The NSQIP registry CEA scale included 14 variables; the highest points were allocated for insulin-dependent diabetes mellitus, high-risk cardiac physiological characteristics, admission source other than home, an emergent operation, American Society of Anesthesiologists' classification IV to V, modified Rankin Scale score >= 2, and presentation with a stroke. NSQIP registry CEA score was predictive of an adverse event (concordance=0.67), stroke or death (concordance=0.69), mortality (concordance=0.76), an extended hospitalization (concordance=0.73), and a nonroutine discharge (concordance=0.83) in the validation population, as well as among symptomatic and asymptomatic subgroups (P<0.001). In the validation population, patients with an NSQIP registry CEA scale score >8 and 17 had 30-day stroke or death rates >3% and 6%, the recommended thresholds for asymptomatic and symptomatic patients, respectively. Conclusions-The NSQIP registry CEA scale predicts adverse outcomes after CEA and can risk stratify patients with both symptomatic and asymptomatic carotid stenosis using different thresholds for each population.