Background and Purpose-Because there is considerable variation in practice patterns and outcomes for carotid endarterectomy (CE), there is a need to study the processes of care that are associated with adverse outcomes. The purpose of this study was to examine the impact of processes of care and surgical specialty on adverse outcomes for CE. Methods-A retrospective cohort study based on a voluntary CE registry containing 3644 patients undergoing CE between April 1, 1997, and March 31, 1999, in New York hospitals was used in the study. A multivariable statistical model was used to identify significant independent patient risk factors and to examine the association of processes of care and surgical specialty with outcomes after adjustment for differences in patient risk factors. Results-The overall adverse outcome (in-hospital death or stroke) rate was 1.84%. After adjustment for differences in 7 patient risk factors that were significantly related to adverse outcomes, the use of Ն1 specific processes of care (eversion endarterectomy, protamine, or shunts) was found to be associated with lower odds of an adverse outcome relative to patients undergoing CE without the processes (ORϭ0. 42, Pϭ0.006). Similarly, patients undergoing surgery performed by vascular surgeons had lower odds of experiencing an adverse outcome (ORϭ0.36, Pϭ0.009). Processes of care and surgical specialty were highly correlated with one another. Conclusions-Processes of care and surgical specialty are significant interrelated determinants of adverse outcome for CE.