Nurse anesthetists (CRNAs) are a lower cost substitute for anesthesiologists in the delivery of anesthesia services. This article addresses the question of when anesthesiologists delegate in a team approach as opposed to using a solo arrangement. Logistic regression analysis was done using data from the 1986 Anesthesia Practice Survey and revealed that the team approach is more likely in areas with a relatively large supply of CRNAs; in hospitals with large surgical volumes, teaching facilities, and public hospitals; during emergency procedures, more lengthy procedures, and less complex surgeries; and among patients with poorer preoperative physical status. However, as the supply of anesthesiologists increases, the probability of CRNA use declines and in areas outside New England the “solo anesthesiologist” arrangement is significantly more common. Medicare and other third-party payers should eliminate regional variations in provider mix that are due to locational preferences and provider attitudes. Delegation to CRNAs can be encouraged by reducing what anesthesiologists are paid for practicing alone.