Purpose: Incident learning systems are important tools to improve patient safety in radiation oncology, but physician participation in these systems is poor. To understand reporting practices and attitudes, a survey was sent to staff members of four large academic radiation oncology centers, all of which have in-house reporting systems. Methods: Institutional review board approval was obtained to send a survey to employees including physicians, dosimetrists, nurses, physicists, and radiation therapists. The survey evaluated barriers to reporting, perceptions of errors, and reporting practices. The responses of physicians were compared with those of other professional groups. Results: There were 274 respondents to the survey, with a response rate of 81.3%. Physicians and other staff agreed that errors and near-misses were happening in their clinics (93.8% v 88.7%, respectively) and that they have a responsibility to report (97% overall). Physicians were significantly less likely to report minor near-misses (P = .001) and minor errors (P = .024) than other groups. Physicians were significantly more concerned about getting colleagues in trouble (P = .015), liability (P = .009), effect on departmental reputation (P = .006), and embarrassment (P < .001) than their colleagues. Regression analysis identified embarrassment among physicians as a critical barrier. If not embarrassed, participants were 2.5 and 4.5 times more likely to report minor errors and major near-miss events, respectively. Conclusions: All members of the radiation oncology team observe errors and near-misses. Physicians, however, are significantly less likely to report events than other colleagues. There are important, specific barriers to physician reporting that need to be addressed to encourage reporting and create a fair culture around reporting.