PROJECT SUMMARY The United States now performs more robotic surgery than all other countries combined. While the overall volume of robotic surgery has tripled in the past decade, its use for the most common general surgery operations (e.g. inguinal hernia repair or gallbladder removal) has increased more than 24- fold over this same period. Despite this, evidence regarding the use and clinical outcomes of robotic surgery for these operations is limited – putting patients at risk between enthusiasm for a new surgical technology and insufficient evidence to justify large changes in clinical practice. Existing observational studies lack appropriate controls and the small number of randomized trials focus on narrow clinical domains (e.g. surgery for rectal cancer) with carefully selected patients and the most experienced surgeons. This proposal uses a combination of Medicare and private payer claims data to characterize the real-world adoption, outcomes, and health care expenditures of robotic surgery for common general surgical operations. We focus on inguinal/ventral hernia repair, cholecystectomy, and surgery for colon and rectal cancer – the clinical domains experiencing the largest growth in robotic surgery. We leverage natural variation in the regional adoption of robotic surgery as an instrumental variable to mitigate issues of selection bias that limit prior observational studies estimating the outcomes of robotic surgery. We use this approach to explore the short-term comparative safety (e.g. incidence of postoperative complications), spending for the surgical episode of care, and long-term effectiveness (e.g. hernia recurrence) of robotic surgery relative to the more established laparoscopic and open approaches for each operation. We assess for heterogeneity in outcomes across surgeons with varying degrees of experience performing robotic surgeries. The results from this study will have immediate relevance to patients and providers making treatment decisions around the safest and most effective approach for surgery. It will also inform the work of policymakers and professional societies who share a common interest in ensuring the safe diffusion of new surgical technologies. Finally, these data will provide public and private payers – who are jointly moving towards greater use of evidence-based coverage design – with data to improve the value of expensive surgical interventions in the United States.