The medical center experienced 8 wrong site/procedure/patient events between April 2008 and January 2010. A common cause analysis (CCA) was conducted on all 8 events to determine the causal factors of these events. After a sentinel event is identified, the medical center conducts a root cause analysis (RCA) within 45 days of the event. A CCA helps recognize trends and establish themes identified from each RCA. The CCA revealed that there were 22 occurrences of failure modes noted in the category of Rules, Policies, and Procedures and 17 failure modes present in the category of Human Factors: Scheduling and Fatigue. A multidisciplinary team was assembled to confirm the failure modes identified in the CCA and to develop processes to address these failure modes. No further wrong site, procedure, or person events have occurred over the last year.