An additional study by the Joint Commission has led to new categorization of sentinel events by setting. From 2005 to the first half of 2019, over 12,000 sentinel events have been reported to the Joint Commission. Categorizing sentinel events by setting found more sentinel events are reported by hospitals than any other health care setting, while 7% of all reported sentinel events were reported in either ambulatory care or ambulatory surgery centers. It is important to recognize, however, that because the reporting of sentinel events is voluntary, the different proportion only means that more were reported from that setting, not that they occur more frequently. Accredited organizations are strongly encouraged, but not required, to report sentinel events to The Joint Commission to learn from these events and share what was learned to help prevent reoccurrence. When looking at the most frequently reported sentinel events from ambulatory care organizations in 2018 and first half of 2019, there are similarities to those reported from hospitals. Wrong site events and unintended foreign object retention are the most frequently reported types of sentinel events for both ambulatory care organizations and hospitals.