Background Educating residents in the operating room requires balancing patient safety, operating room efficiency demands, and resident learning needs. This study explores 4 factors that influence the amount of autonomy supervising surgeons afford to residents. Methods We evaluated 7,297 operations performed by 487 general surgery residents and evaluated by 424 supervising surgeons from 14 training programs. The primary outcome measure was supervising surgeon autonomy granted to the resident during the operative procedure. Predictor variables included resident performance on that case, supervising surgeon history with granting autonomy, resident training level, and case difficulty. Results Resident performance was the strongest predictor of autonomy granted. Typical autonomy by supervising surgeon was the second most important predictor. Each additional factor led to a smaller but still significant improvement in ability to predict the supervising surgeon's autonomy decision. The 4 factors together accounted for 54% of decision variance (r = 0.74). Conclusion Residents’ operative performance in each case was the strongest predictor of how much autonomy was allowed in that case. Typical autonomy granted by the supervising surgeon, the second most important predictor, is unrelated to resident proficiency and warrants efforts to ensure that residents perform each procedure with many different supervisors.