Objective To evaluate the comparative safety of laparoscopic and open colectomy across surgeons varying in experience with laparoscopy. Data Sources National Medicare data (2008–2010) for beneficiaries undergoing laparoscopic or open colectomy. Study Design Using instrumental variable methods to address selection bias, we evaluated outcomes of laparoscopic and open colectomy. Our instrument was the regional use of laparoscopy in the year prior to a patient's operation. We then evaluated outcomes stratified by surgeons' annual volume of laparoscopic colectomy. Principal Findings Laparoscopic colectomy was associated with lower mortality (OR: 0.75, 95 percent CI: 0.70–0.78) and fewer complications than open surgery (OR: 0.82, 95 percent CI: 0.79–0.85). Increasing surgeon volume was associated with better outcomes for both procedures, but the relationship was stronger for laparoscopy. The comparative safety depended on surgeon volume. High‐volume surgeons had 40 percent lower mortality (OR: 0.60, 95 percent CI: 0.55–0.65) and 30 percent fewer complications (OR: 0.70, 95 percent CI: 0.67–0.74) with laparoscopy. Conversely, low‐volume surgeons had 7 percent higher mortality (OR: 1.07, 95 percent CI: 1.02–1.13) and 18 percent more complications (OR: 1.18, 95 percent CI: 1.12–1.24) with laparoscopy. Conclusions This population‐based study demonstrates that the comparative safety of laparoscopic and open colectomy is influenced by surgeon volume. Laparoscopic colectomy is only safer for patients whose surgeons have sufficient experience.