OBJECTIVE : We evaluated patterns of event reporting across five clinical locations within an academic radiation oncology department, with the goal of better understanding variability across sites. METHODS : We analyzed 1,351 events reported to a departmental incident learning system over 1 calendar year across the five locations with respect to volume of events, event type, process map location of origin and detection, and event reporter. RESULTS : We found marked variability in reporting patterns, including reporting rate, event type, event severity, event location of origin and detection within the departmental process map, and discipline of event reporters. These differences relate both to variability in process and workflow (reflected by frequency of specific workflow events at each site) and in reporting culture (reflected by volume or rate of event reporting, and discipline of event reporter). CONCLUSIONS : These data highlight the variability in reporting culture even within a single department, and therefore the need to tailor and individualize safety and quality programs to the unique clinical site, with the long-term goal of achieving a common culture of safety while supporting unique processes at individual locations. This work also raises concern about extrapolating single-institution incident learning system results without understanding the unique workflow and culture of clinical sites.